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1.
BMC Genomics ; 25(1): 564, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38840037

RESUMEN

Mesenchymal Stem Cells are ideal seed cells for tissue repair and cell therapy and have promising applications in regenerative medicine and tissue engineering. Using Platelet-Rich Plasma as an adjuvant to create and improve the microenvironment for Mesenchymal Stem Cells growth can enhance the biological properties of Mesenchymal Stem Cells and improve the efficacy of cell therapy. However, the mechanism by which Platelet-Rich Plasma improves the biological performance of Mesenchymal Stem Cells is still unknown. In this study, by examining the effects of Platelet-Rich Plasma on the biological performance of Mesenchymal Stem Cells, combined with multiomics analysis (Transcriptomics, Proteomics and Metabolomics) and related tests, we analyzed the specific pathways, related mechanisms and metabolic pathways of Platelet-Rich Plasma to improve the biological performance of Mesenchymal Stem Cells. In an in vitro cell culture system, the biological performance of Mesenchymal Stem Cells was significantly improved after replacing Foetal Bovine Serum with Platelet-Rich Plasma, and the genes (ESM1, PDGFB, CLEC7A, CCR1 and ITGA6 et al.) related to cell proliferation, adhesion, growth, migration and signal transduction were significantly upregulated. Platelet-Rich Plasma can enhance the secretion function of MSC exosomes, significantly upregulate many proteins related to tissue repair, immune regulation and anti-infection, and enhance the repair effect of exosomes on skin injury. After replacing Foetal Bovine Serum with Platelet-Rich Plasma, Mesenchymal Stem Cells underwent metabolic reprogramming, the metabolism of amino acids and fatty acids and various signaling pathways were changed, the anabolic pathways of various proteins were enhanced. These results provide a theoretical and technical reference for optimizing the Mesenchymal Stem Cells culture system, improving the biological characteristics and clinical application effects of Mesenchymal Stem Cells.


Asunto(s)
Proliferación Celular , Células Madre Mesenquimatosas , Plasma Rico en Plaquetas , Proteómica , Células Madre Mesenquimatosas/metabolismo , Células Madre Mesenquimatosas/citología , Plasma Rico en Plaquetas/metabolismo , Humanos , Metabolómica , Animales , Células Cultivadas , Perfilación de la Expresión Génica , Exosomas/metabolismo , Multiómica
2.
J Am Chem Soc ; 146(40): 27287-27292, 2024 Oct 09.
Artículo en Inglés | MEDLINE | ID: mdl-39348600

RESUMEN

Birefringent crystals hold a significant position in optical and optoelectronic fields due to their capability to control polarized light. Despite various chemical strategies devoted to designing birefringent crystals, it remains a challenge to switch and manipulate birefringence under physical stimuli. Here we present an unusual triple-state switching of birefringence in a 2D perovskite ferroelectric, (N-methylcyclohexylammonium)2PbCl4 (1), which exhibits two reversible phase transitions at 361 and 373 K. The in-plane birefringence of 1 (Δnbc) shows three distinctive states inside the bc plane, namely, the low-, high-, and zero-Δnbc states. Strikingly, a huge augmentation of Δnbc is solidly confirmed up to ∼400% between its low and high states, far beyond other birefringent materials. The origin of this triple-state switching of birefringence involves the variation of the ferroelastic strain and domain in the vicinity of the phase transition. As an entirely new mode of switching birefringence, this work facilitates the further development of new intelligent nonlinear optics.

3.
J Am Chem Soc ; 146(12): 8298-8307, 2024 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-38498306

RESUMEN

Antiferroelectric materials with an electrocaloric effect (ECE) have been developed as promising candidates for solid-state refrigeration. Despite the great advances in positive ECE, reports on negative ECE remain quite scarce because of its elusive physical mechanism. Here, a giant negative ECE (maximum ΔS ∼ -33.3 J kg-1 K-1 with ΔT ∼ -11.7 K) is demonstrated near room temperature in organometallic perovskite, iBA2EA2Pb3I10 (1, where iBA = isobutylammonium and EA = ethylammonium), which is comparable to the greatest ECE effects reported so far. Moreover, the ECE efficiency ΔS/ΔE (∼1.85 J cm kg-1 K-1 kV-1) and ΔT/ΔE (∼0.65 K cm kV-1) are almost 2 orders of magnitude higher than those of classical inorganic ceramic ferroelectrics and organic polymers, such as BaTiO3, SrBi2Ta2O9, Hf1/2Zr1/2O2, and P(VDF-TrFE). As far as we know, this is the first report on negative ECE in organometallic hybrid perovskite ferroelectric. Our experimental measurement combined with the first-principles calculations reveals that electric field-induced antipolar to polar structural transformation results in a large change in dipolar ordering (from 6.5 to 45 µC/cm2 under the ΔE of 18 kV/cm) that is closely related to the entropy change, which plays a key role in generating such giant negative ECE. This discovery of field-induced negative ECE is unprecedented in organometallic perovskite, which sheds light on the exploration of next-generation refrigeration devices with high cooling efficiency.

4.
Small ; 20(24): e2310529, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38148294

RESUMEN

2D organic-inorganic hybrid perovskites (OIHPs) have become one of the hottest research topics due to their excellent environmental stability and unique optoelectronic properties. Recently, the ferroelectricity and thermochromism of 2D OIHPs have attracted increasing interests. Integrating ferroelectricity and thermochromism into perovskites can significantly promote the development of multichannel intelligent devices. Here, a novel 2D Dion-Jacobson OIHP of the formula (3AMP)PbI4 (where 3AMP is 3-(aminomethyl)pyridinium) is reported, which has a remarkable spontaneous polarization value (Ps) of 15.6 µC cm-2 and interesting thermochromism. As far it is known, such a large Ps value is the highest for 2D OIHPs recorded so far. These findings will inspire further exploration and application of multifunctional perovskites.

5.
Phys Rev Lett ; 132(26): 262301, 2024 Jun 28.
Artículo en Inglés | MEDLINE | ID: mdl-38996277

RESUMEN

The hexadecapole deformation (ß_{4}) of the ^{238}U nucleus has not been determined because its effect is overwhelmed by those from the nucleus' large quadrupole deformation (ß_{2}) in nuclear electric transition measurements. In this Letter, we identify the nonlinear response of the hexadecapole anisotropy to ellipticity in relativistic U+U collisions that is solely sensitive to ß_{4} and insensitive to ß_{2}. We demonstrate this by state-of-the-art hydrodynamic calculations and discuss the prospects of discovering the ß_{4} of ^{238}U in heavy-ion data at the Relativistic Heavy Ion Collider.

6.
Chemphyschem ; : e202400801, 2024 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-39411953

RESUMEN

Molecular ferroelectrics are emerging as a robust family of electric-ordered materials due to their distinct structural flexibility, molecular tunability, and versatility. In recent years, diverse chemical design approaches have significantly contributed to discovering and optimizing ferroelectric performances of molecule-based ferroelectric systems. Notably, halogen substitution is one of the most effective strategies for inducing symmetry breaking and optimizing the dipole moments and potential energy barriers. In this minireview, we have summarized recent significant advances of halogen substitution strategy in molecule-based ferroelectrics, including organic-inorganic hybrids and metal-free molecular systems. Subsequently, we discuss the underlying mechanism of halogen substitution to improve ferroelectric performances, including the generation of spontaneous polarization, enhancement of Curie temperature, and bandgap engineering. Finally, the future directions in designing and modulating molecular ferroelectrics by halogen substitution strategy are also highlighted.

7.
Angew Chem Int Ed Engl ; : e202417036, 2024 Oct 16.
Artículo en Inglés | MEDLINE | ID: mdl-39413042

RESUMEN

Polar molecular crystals hold a promise for controlling bulk physical properties originated in their unique switchable polarity via structural transformation. However, the mechanisms for switching polarization are mainly limited to displacive and disorder-order phase transitions, which rarely involve the reconstruction of chemical bonds. Here, we have switched and tuned electric polarization in a bimetallic halide, (Neopentylammonium)4AgBiBr8 (1), as verified by light-excited pyroelectric effect. Most notably, its Ag-Br coordination bonds show a zipper-like dynamic switching behavior from the 'locked' to 'unlocked' state, namely, reconstruction of chemical bonds. Coupling with the dynamic ordering of organic cations, this bond-switching transition makes a contribution to switchable polarization of 1. As expected, its polarity creates pyroelectric effect for self-driven X-ray detection with high sensitivity (3.8×103 µC Gy-1 cm-2) and low limit of detection (4.8 nGy s-1). This work on the bond-switching mechanism provides an avenue to design polar molecular candidate for smart optoelectronic devices.

8.
Angew Chem Int Ed Engl ; 63(14): e202401221, 2024 Apr 02.
Artículo en Inglés | MEDLINE | ID: mdl-38342759

RESUMEN

Metal-free molecular antiferroelectric (AFE) holds a promise for energy storage on account of its unique physical attributes. However, it is challenging to explore high-curie temperature (Tc) molecular AFEs, due to the lack of design strategies regarding the rise of phase transition energy barriers. By renewing the halogen substitution strategy, we have obtained a series of high-Tc molecular AFEs of the halogen-substituted phenethylammonium bromides (x-PEAB, x=H/F/Cl/Br), resembling the binary stator-rotator system. Strikingly, the p-site halogen substitution of PEA+ cationic rotators raises their phase transition energy barrier and greatly enhances Tc up to ~473 K for Br-PEAB, on par with the record-high Tc values for molecular AFEs. As a typical case, the member 4-fluorophenethylammonium bromide (F-PEAB) shows notable AFE properties, including high Tc (~374 K) and large electric polarization (~3.2 µC/cm2). Further, F-PEAB also exhibits a high energy storage efficiency (η) of 83.6 % even around Tc, catching up with other AFE oxides. This renewing halogen substitution strategy in the molecular AFE system provides an effective way to design high-Tc AFEs for energy storage devices.

9.
Angew Chem Int Ed Engl ; 63(7): e202318742, 2024 Feb 12.
Artículo en Inglés | MEDLINE | ID: mdl-38153344

RESUMEN

Recently, boron (B)/nitrogen (N)-embedded polycyclic aromatic hydrocarbons (PAHs), characterized by multiple resonances (MR), have attracted significant attention owing to their remarkable features of efficient narrowband emissions with small full width at half maxima (FWHMs). However, developing ultra-narrowband pure-green emitters that comply with the Broadcast Service Television 2020 (BT2020) standard remains challenging. Precise regulation of the MR distribution regions allows simultaneously achieving the emission maximum, FWHM value, and spectral shape that satisfy the BT2020 standard. The proof-of-concept molecule TPABO-DICz exhibited ultrapure green emission with a dominant peak at 515 nm, an extremely small FWHM of 17 nm, and Commission Internationale de l'Eclairage (CIE) coordinates of (0.17, 0.76). The corresponding bottom-emitting organic light-emitting diode (OLED) exhibited a remarkably high CIEy value (0.74) and maximum external quantum efficiency (25.8 %). Notably, the top-emitting OLED achieved nearly BT2020 green color (CIE: 0.14, 0.79) and exhibited a state-of-the-art maximum current efficiency of 226.4 cd A-1 , thus fully confirming the effectiveness of the above strategy.

10.
Small ; 19(46): e2304190, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37452433

RESUMEN

Metal halide inorganic perovskites show excellent thermal stability compared to organic-inorganic perovskites. However, the performance of inorganic perovskite solar cells (PSCs) is far from theoretical values, together with unsatisfactory stability, mainly due to the poor interfacial properties. In this work, a facial but effective method is reported to realize high-performance inorganic PSCs by post-modifying the perovskite surface with 2-thiophene ethylamine (TEA). It is found that amine group from TEA can favorably interact with the undercoordinated Pb2+ via Lewis acid-based coordination, while thiophene ring with electron-rich sulfur assists such interaction by functioning as an electron donor. The synergetic interaction allows TEA to passivate perovskite film defects more efficiently, as compared to phenethylamine (PEA) with less electron-donating ability. Moreover, perovskite valence band is slightly upward shift to match with hole transport material and facilitate hole transfer. These combinations result in a reduced non-radiative charge recombination and improved charge carrier lifetime. Consequently, PSCs with TEA modification shows a drastic improvement of VOC by 54 mV, yielding a champion PCE of 21.3%, much higher than the control PSCs (19.3%), along with improved ambient stability. This work demonstrates that surface modifier with an electron-rich moiety is critical for achieving efficient and stable inorganic PSCs.

11.
Small ; 19(16): e2207393, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36651018

RESUMEN

The bulk anomalous photovoltaic (BAPV) effect of acentric materials refers to a distinct concept from traditional semiconductor-based devices, of which the above-bandgap photovoltage hints at a promise for solar-energy conversion. However, it is still a challenge to exploit new BAPV-active systems due to the lacking of knowledge on the structural origin of this concept. BAPV effects in single crystals of a 2D lead-free double perovskite, (BBA)2 CsAgBiBr7 (1, BBA = 4-bromobenzylammonium), tailored by mixing aromatic and alkali cations in the confined architecture to form electric polarization are acquired here. Strikingly, BAPV effects manifested by above-bandgap photovoltage (VOC ) show unique attributes of directional anisotropy and positive dependence on electrode spacing. The driving source stems from orientations of the polar aromatic spacer and Cs+ ion drift, being different from the known built-in asymmetry photovoltaic heterojunctions. As the first demonstration of the BAPV effect in the double perovskites, the results will enrich the family of environmentally green BAPV-active candidates and further facilitate their new optoelectronic application.

12.
Small ; 19(34): e2301594, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37086129

RESUMEN

2D Dion-Jacobson (DJ) phase hybrid perovskites have shown great promise in the photoelectronic field owing to their outstanding optoelectronic performance and superior structural rigidity. However, DJ phase lead-free double perovskites are still a virgin land with direct X-ray detection. Herein, we have designed and synthesized a new DJ phase lead-free layered double perovskite of (HIS)2 AgSbBr8 (1, HIS2+  = histammonium). Centimeter-sized (18 × 10 × 5 mm3 ) single crystals of 1 are successfully grown via the temperature cooling technique, exhibiting remarkable semiconductive characteristics such as a high resistivity (2.2 × 1011  Ω cm), a low trap state density (3.56 × 1010 cm-3 ), and a large mobility-lifetime product (1.72 × 10-3 cm2 V-1 ). Strikingly, its single-crystal-based X-ray detector shows a high sensitivity of 223 µC Gy-1 air cm-2 under 33.3 V mm-1 , a low detection limit (84.2 nGyair s-1 ) and superior anti-fatigue. As far as we know, we firstly demonstrates the potential of 2D DJ phase lead-free hybrid double perovskite in X-ray detection, showing excellent photoelectric response and operational stability. This work will pave a promising pathway to the innovative application of hybrid perovskites for eco-friendly and efficient X-ray detection.

13.
Small ; 19(49): e2303909, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-37612806

RESUMEN

Photorefractive effect of ferroelectrics refers to the light-induced change of refractive index, which is an optical controlling avenue in holographic storage and image processing. For most ferroelectrics, however, the small photorefractive effect (10-5 -10-4 ) hinders their practical application and it is urgent to exploit new photorefractive system. Here, for the first time, strong photorefractive effects are achieved in a 2D metal-halide ferroelectric, [CH3 (CH2 )3 NH3 ]2 (CH3 NH3 )Pb2 Cl7 (1), showing large spontaneous polarization (≈4.1 µC cm-2 ) and wide optical bandgap (≈3.20 eV). Notably, under light irradiation, 1 enables a large variation of refractive indices up to ≈ 1× 10-3 , being one order higher than the existing materials and comparable to the state-of-the-art inorganic ferroelectrics. This intriguing photorefractive behavior involves with the sharp variation of polarization caused by photo-pyroelectricity. As the first report of 2D metal-halide photorefractive ferroelectric, this work sheds light on optical controlling of physical properties in electric-ordered materials.

14.
Opt Express ; 31(15): 24273-24282, 2023 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-37475258

RESUMEN

The bandgap and polarization field play a key role in the ferroelectric photovoltaic effect. However, narrow bandgap induced electrical conductivity always brings out a depression of the photovoltaic performances. Based on the mechanisms of the photovoltaic effect and resistance switching behaviors in ferroelectric materials, this work realizes an evolution between the two effects by engineering the polarization field and barrier characteristics, which addresses the trade-off issues between the bandgap and polarization for ferroelectric photovoltaic effect. SrCoOx (SC, 2.5≤x≤3) with multivalent transition is introduced into Na0.5Bi0.5TiO3 (NBT) matrix material to engineered the polarization field and barrier characteristics. (1-x)NBT-xSC (x=0.03, 0.05, 0.07) solid solution films present an evolution of ferroelectric photovoltaic effect to grow out of nothing again to the disappearance of the photovoltaic effect and the appearance of resistance switching behavior. The 0.95NBT-0.05SC film achieve the open-circuit voltage of 0.81 V and the short-circuit current of 23.52 µA/cm2, and the 0.93NBT-0.07SC film obtains the resistive switching behavior with switch ratio of 100. This work provides a practicable strategy to achieve the fascinating evolution between photovoltaic effect and resistive switching.

15.
Chemistry ; 29(33): e202300876, 2023 Jun 13.
Artículo en Inglés | MEDLINE | ID: mdl-37062802

RESUMEN

Two-dimensional (2D) hybrid perovskite materials have been widely used for polarization-sensitive photodetection due to their fascinating optical and physical attributes. However, studies on those materials that enable strong polarized-light activities under a weak-light condition remain quite scarce. Here, by tailoring aromatic cation into 3D prototype, we have successfully obtained a new 2D hybrid perovskite, (FPEA)2 (MA)Pb2 Br7 (1, where FPEA is 4-fluorophenethylammonium and MA is methylammonium). The alternative alignment of inorganic and organic structural components results in significant anisotropy, including optical absorption and electric conductivity. The coupling effect of these anisotropic properties in 1 gives rise to strong dichroic activities toward detecting polarized light. Especially, under weak light intensity (∼330 nW/cm2 ), it can still generate a large polarization ratio up to 1.35, which is even higher than those of some typical 2D materials (i. e., GeSe ∼1.09). Besides, single crystal-based photodetector of 1 displays fascinating detecting performances, including large photocurrent on/off ratio (∼104 ), fast response time (∼154/182 µs) and excellent antifatigued stability. These findings disclose the potentials of 1 as a robust candidate for detecting weak polarized light, which has practical applications in the field of polarized optoelectronics.


Asunto(s)
Compuestos de Calcio , Luz , Anisotropía , Conductividad Eléctrica
16.
Anal Biochem ; 679: 115297, 2023 10 15.
Artículo en Inglés | MEDLINE | ID: mdl-37619903

RESUMEN

Accumulating evidence suggests that long non-coding RNAs (lncRNAs) are associated with various complex human diseases. They can serve as disease biomarkers and hold considerable promise for the prevention and treatment of various diseases. The traditional random walk algorithms generally exclude the effect of non-neighboring nodes on random walking. In order to overcome the issue, the neighborhood constraint (NC) approach is proposed in this study for regulating the direction of the random walk by computing the effects of both neighboring nodes and non-neighboring nodes. Then the association matrix is updated by matrix multiplication for minimizing the effect of the false negative data. The heterogeneous lncRNA-disease network is finally analyzed using an unbalanced random walk method for predicting the potential lncRNA-disease associations. The LUNCRW model is therefore developed for predicting potential lncRNA-disease associations. The area under the curve (AUC) values of the LUNCRW model in leave-one-out cross-validation and five-fold cross-validation were 0.951 and 0.9486 ± 0.0011, respectively. Data from published case studies on three diseases, including squamous cell carcinoma, hepatocellular carcinoma, and renal cell carcinoma, confirmed the predictive potential of the LUNCRW model. Altogether, the findings indicated that the performance of the LUNCRW method is superior to that of existing methods in predicting potential lncRNA-disease associations.


Asunto(s)
Neoplasias Renales , ARN Largo no Codificante , Humanos , ARN Largo no Codificante/genética , Algoritmos , Área Bajo la Curva , Caminata
17.
Lupus ; 32(4): 477-488, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36749733

RESUMEN

OBJECTIVE: To investigate the dietary patterns and lifestyles of patients with lupus gastrointestinal (GI) involvement and to reveal the possible role of organ-specific involvement of systemic lupus erythematosus (SLE) on daily diet. METHODS: Patients with SLE complicated with gastrointestinal involvement (SLE-GI) admitted to Peking Union Medical College Hospital (PUMCH) from January 2010 to September 2021 were enrolled. Age- and sex-matched SLE patients with lupus nephritis (SLE-LN) but free of other internal organs involvement who were admitted during the same period were enrolled as disease controls at the ratio of 1:1. In addition, a group of age- and sex-matched healthy people were also included as healthy controls (HCs). Questionnaires were distributed to these patients and HC to collect their dietary patterns and lifestyle information. Clinical features, dietary and lifestyle habits were compared between the two groups of patients and HC. RESULTS: The questionnaire survey showed that compared with HC, the SLE-GI group had higher proportions of vegetarians (p = 0.014) and a lower proportion of omnivores (p = 0.058). A higher percentage of SLE-GI patients reported a traditional Chinese medicine (p = 0.018) taken history and surgical history (p = 0.014). They also less likely to take fried/pickled food (p = 0.042) and dietary supplements (p = 0.024) than HC. Higher percentages of SLE-GI patients and SLE-LN patients preferred self-catering (87.5% and 94.3%) over take-out food than HC (70.8%) (p = 0.127 and p = 0.016). No significant difference on drinking preference among the three groups, but it seemed more SLE-GI patients consumed yogurt than HC (p = 0.097). The SLE-LN patients were also found to have lower frequencies of staying up late (p = 0.005). The SLE-GI group also presented higher positivity rates for anti-SSA (69.6% vs. 45.7%, p = 0.020) and anti-SSB antibodies (32.6% vs. 10.9%, p = 0.011) but lower positivity rates for anti-dsDNA antibodies (30.4% vs. 82.6%, p < 0.001) compared with the SLE-LN group. CONCLUSION: The dietary patterns, life-styles and autoantibody spectrum of SLE-GI patients differed greatly from those of SLE-LN patients and healthy people. These factors may reflect the influence of disease and organ involvement modes on patients' daily life and may contribute partly to the systemic involvement in SLE.


Asunto(s)
Lupus Eritematoso Sistémico , Nefritis Lúpica , Humanos , Lupus Eritematoso Sistémico/complicaciones , Nefritis Lúpica/complicaciones , China/epidemiología , Autoanticuerpos , Encuestas y Cuestionarios
18.
J Environ Manage ; 339: 117856, 2023 Aug 01.
Artículo en Inglés | MEDLINE | ID: mdl-37129968

RESUMEN

With increasing human impacts on the ecosystem in natural protected areas, there is an urgent need to undertake an assessment of ecological carrying capacity taken as a benchmark for assessing regional sustainability. Based on satellite remote sensing and socio-economic statistical data from 2000 to 2019, this study distinguished the controlling factors for the spatial and temporal patterns of ecological carrying capacity in the Qilian Mountain National Park, one of the 10 pilot national parks in China. The ecological carrying capacity index (ECCI) was developed by using the Driver-Pressure-State-Impact-Response framework and a comprehensive weight method. The results showed that the multiyear averaged ECCI was low in the south and west but was high in central and eastern regions. The spatial distribution of the ECCI was constrained by soil resources, ecosystem quality, land use/cover and water environment. At the regional scale, the ECCI decreased from 2000 to 2014, especially in Tianzhu, where farmland expansion and severe droughts reduced habitat quality and ecosystem function. However, the ECCI increased significantly from 2014 to 2019, which was attributed to a warm moist climate and the implementation of eco-environmental protection policies. Forest and grassland coverage, soil and water conservation, waste water treatment amount and terrestrial water reserves accounted for 35%, 26%, 20% and 8%, respectively, of the temporal variability in the ECCI. Concurrent with national park development, the ECCI is predicted to increase in most areas from 2020 to 2029 by back-propagation artificial neural networks, except for Sunan, Shandan and Menyuan, possibly owing to increasing conflicts between humans and the environment. The findings of this study provide evidence about the effectiveness of government policies in promoting regional sustainability by altering ecosystem composition and function. In addition, the dominant drivers for the temporal variability of ecological carrying capacity varied in space according to stepwise regression analysis, calling for region-specific management strategies in mountain protected areas and their surroundings.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Humanos , Conservación de los Recursos Naturales/métodos , Parques Recreativos , China , Suelo
19.
Angew Chem Int Ed Engl ; 62(17): e202300028, 2023 Apr 17.
Artículo en Inglés | MEDLINE | ID: mdl-36809685

RESUMEN

As a momentum-independent spin configuration, persistent spin texture (PST) could avoid spin relaxation and play an advantageous role in spin lifetime. Nevertheless, manipulation of PST is a challenge due to the limited materials and ambiguous structure-property relationships. Herein, we present electrically switchable PST in a new 2D perovskite ferroelectric, (PA)2 CsPb2 Br7 (where PA is n-pentylammonium), which has a high Curie temperature of 349 K, evident spontaneous polarization (3.2 µC cm-2 ) and a low coercive electric field of 5.3 kV cm-1 . The combination of symmetry-breaking in ferroelectrics and effective spin-orbit field facilitates intrinsic PST in the bulk and monolayer structure models. Strikingly, the directions of spin texture are reversible by switching the spontaneous electric polarization. This electric switching behavior relates to the tilting of PbBr6 octahedra and the reorientation of organic PA+ cations. Our studies on ferroelectric PST of 2D hybrid perovskites afford a platform for electrical spin texture manipulation.

20.
Angew Chem Int Ed Engl ; 62(45): e202309416, 2023 Nov 06.
Artículo en Inglés | MEDLINE | ID: mdl-37733923

RESUMEN

Ferroelectric photovoltaics driven by spontaneous polarization (Ps ) holds a promise for creating the next-generation optoelectronics, spintronics and non-volatile memories. However, photoactive ferroelectrics are quite scarce in single homogeneous phase, owing to the severe Ps fatigue caused by leakage current of photoexcited carriers. Here, through combining inorganic and organic components as building blocks, we constructed a series of ferroelectric semiconductors of 2D hybrid perovskites, (HA)2 (MA)n-1 Pbn Br3n+1 (n=1-5; HA=hexylamine and MA=methylamine). It is intriguing that their Curie temperatures are greatly enhanced by reducing the thickness of inorganic frameworks from MAPbBr3 (n=∞, Tc =239 K) to n=2 (Tc =310 K, ΔT=71 K). Especially, on account of the coupling of room-temperature ferroelectricity (Ps ≈1.5 µC/cm2 ) and photoconductivity, n=3 crystal wafer was integrated as channel field effect transistor that shows excellent a large short-circuit photocurrent ≈19.74 µA/cm2 . Such giant photocurrents can be modulated through manipulating gate voltage in a wide range (±60 V), exhibiting gate-tunable memory behaviors of three current states ("-1/0/1" states). We believe that this work sheds light on further exploration of ferroelectric materials toward new non-volatile memory devices.

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