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1.
Front Public Health ; 12: 1437647, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39091532

RESUMO

Introduction: How to scientifically assess the health status of cities and effectively assist in formulating policies and planning for health city development remains a profound challenge in building a global "health community." Methods: This study employs the Building Research Establishment's International Healthy Cities Index (BRE HCI), encompassing ten environmental categories and fifty-eight indicators, to guide and support the scientific development of healthy cities. The entropy weight-TOPSIS method and the rank sum ratio (RSR) method were applied to comprehensively rank and categorize the health development levels of fifteen global cities. Furthermore, through cluster analysis, this research identifies universal and unique indicators that influence the development of healthy cities. Results: The results indicate that: (1) Within the scope of 58 evaluation indicators, the precedence in weight allocation is accorded to the kilometres of bicycle paths and lanes per 100,000 population (0.068), succeeded by m2 of public indoor recreation space per capita (0.047), and kilometres of bicycle paths and lanes per 100,000 population (0.042). (2) Among the ten environmental categories, the top three in terms of weight ranking are transport (0.239), leisure and recreation (0.172), and resilience (0.125). Significant disparities exist between different cities and environmental categories, with the issue of uneven health development within cities being particularly prominent. (3) The study categorizes the development levels of healthy cities into three tiers based on composite scores: it classifies Singapore, Shanghai, and Amsterdam at an excellent level; places Dubai and Johannesburg at a comparatively poor level; and situates the remaining ten cities at a moderate level. (4) The analysis identifies 53 international common indicators and 5 characteristic indicators from the 58 indicators based on the significance of the clustering analysis (p < 0.05). Discussion: The study proposes four strategic recommendations based on these findings: establishing a comprehensive policy assurance system, refining urban spatial planning, expanding avenues for multi-party participation, and augmenting distinctive health indicators. These measures aim to narrow the developmental disparities between cities and contribute to healthy global cities' balanced and sustainable growth. However, due to existing limitations in sample selection, research methodology application, and the control of potential confounding variables, further in-depth studies are required in the future.


Assuntos
Cidades , Saúde Global , Humanos , Planejamento de Cidades , Saúde da População Urbana
2.
Commun Biol ; 7(1): 1007, 2024 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-39154094

RESUMO

Biological invasions pose a significant threat to ecosystems, disrupting local biodiversity and ecosystem functions. The genomic underpinnings of invasiveness, however, are still largely unknown, making it difficult to predict and manage invasive species effectively. The common reed (Phragmites australis) is a dominant grass species in wetland ecosystems and has become particularly invasive when transferred from Europe to North America. Here, we present a high-quality gap-free, telomere-to-telomere genome assembly of Phragmites australis consisting of 24 pseudochromosomes and a B chromosome. Fully phased subgenomes demonstrated considerable subgenome dominance and revealed the divergence of diploid progenitors approximately 30.9 million years ago. Comparative genomics using chromosome-level scaffolds for three other lineages and a previously published draft genome assembly of an invasive lineage revealed that gene family expansions in the form of tandem duplications may have contributed to the invasiveness of the lineage. This study sheds light on the genome evolution of Arundinoideae grasses and suggests that genetic drivers, such as gene family expansions and tandem duplications, may underly the processes of biological invasion in plants. These findings provide a crucial step toward understanding and managing the genetic basis of invasiveness in plant species.


Assuntos
Cromossomos de Plantas , Evolução Molecular , Genoma de Planta , Espécies Introduzidas , Poaceae , Poaceae/genética , Cromossomos de Plantas/genética , Filogenia , Genômica/métodos
3.
Artigo em Inglês | MEDLINE | ID: mdl-38982692

RESUMO

In eukaryotic cells, primases are the key polymerase during DNA replication and DNA damage repair, which includes primase subunit 1 (PRIM1) and primase subunit 2 (PRIM2). Recent studies reported that the aberrant expression and activity of PRIM enzymes are closely associated with the carcinogenesis and development of various cancers. PRIM1 is overexpressed in hepatocellular carcinoma, breast cancer, and other cancers, while PRIM2 is highly expressed in lung cancer, gastrointestinal cancer, and other cancers. Further studies revealed that the knockdown of PRIM1 promoted the apoptosis of liver cancer cells, while Dihydroartemisinin (DHA) can inhibit PRIM2 expression, suppress lung cancer cell proliferation, and result in ferroptosis. The present review summarized the recent advancements in the research of the aberrant expression of PRIM1 and PRIM2 and their activity in DNA replication, DNA damage repair, and carcinogenesis. Furthermore, the strategies targeting PRIM1 or/and PRIM2 become potential therapeutic approaches in cancer treatment.

4.
Adv Sci (Weinh) ; : e2400196, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38978353

RESUMO

Osteoarthritis is a highly prevalent progressive joint disease that still requires an optimal therapeutic approach. Intermittent fasting is an attractive dieting strategy for improving health. Here this study shows that intermittent fasting potently relieves medial meniscus (DMM)- or natural aging-induced osteoarthritic phenotypes. Osteocytes, the most abundant bone cells, secrete excess neuropeptide Y (NPY) during osteoarthritis, and this alteration can be altered by intermittent fasting. Both NPY and the NPY-abundant culture medium of osteocytes (OCY-CM) from osteoarthritic mice possess pro-inflammatory, pro-osteoclastic, and pro-neurite outgrowth effects, while OCY-CM from the intermittent fasting-treated osteoarthritic mice fails to induce significant stimulatory effects on inflammation, osteoclast formation, and neurite outgrowth. Depletion of osteocyte NPY significantly attenuates DMM-induced osteoarthritis and abolishes the benefits of intermittent fasting on osteoarthritis. This study suggests that osteocyte NPY is a key contributing factor in the pathogenesis of osteoarthritis and intermittent fasting represents a promising nonpharmacological antiosteoarthritis method by targeting osteocyte NPY.

5.
Biomacromolecules ; 25(7): 4557-4568, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38899740

RESUMO

Rheumatoid arthritis (RA) is a complicated chronic disorder of the immune system, featured with severe inflammatory joints, synovium hyperplasia, articular cartilage, and bone damage. In the RA microenvironment, RA-involved cells, overproduced nitric oxide (NO), and pro-inflammatory cytokines are highly interplayed and mutually reinforced, which form a vicious circle and play crucial roles in the formation and progression of RA. To comprehensively break the vicious circle and obtain the maximum benefits, we have developed neutrophil membrane-camouflaged NO scavenging nanoparticles based on an NO-responsive hyaluronic acid derivative for delivery of MTX. These multifunctional nanoparticles (NNO-NPs/MTX), by inheriting the membrane functions of the source cells, possess prolonged circulation and specific localization at the inflamed sites when administrated in the body. Remarkably, NNO-NPs/MTX can neutralize the pro-inflammatory cytokines via the outer membrane receptors, scavenge NO, and be responsively disassociated to release MTX for RA-involved cell regulation and HA for lubrication in the RA sites. In a collagen-induced arthritis mouse model, NNO-NPs/MTX exhibits a significant anti-inflammation effect and effectively alleviates the characteristic RA symptoms such as synovial hyperplasia and cartilage destruction, realizing the synergistic and boosted therapeutic outcome against intractable RA. Thus, NNO-NPs/MTX provides a promising and potent platform to integrately treat RA.


Assuntos
Artrite Reumatoide , Ácido Hialurônico , Metotrexato , Óxido Nítrico , Ácido Hialurônico/química , Animais , Artrite Reumatoide/tratamento farmacológico , Camundongos , Metotrexato/farmacologia , Metotrexato/administração & dosagem , Metotrexato/química , Óxido Nítrico/metabolismo , Nanopartículas/química , Humanos , Artrite Experimental/tratamento farmacológico , Artrite Experimental/patologia , Sistemas de Liberação de Medicamentos/métodos , Nanopartículas Multifuncionais/química , Materiais Biomiméticos/química , Materiais Biomiméticos/farmacologia
6.
Inorg Chem ; 63(27): 12615-12623, 2024 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-38917336

RESUMO

Polynitrogen has been widely studied recently as a rising star of high energy density materials. Here, we performed a systematic study of the Zr-N compounds in the N-rich region by the first-principles method. The high-pressure phase diagram of the Zr-N system is enriched by proposing five new compounds. ZrN10 with the infinitely extended band shaped structure is first reported. The band-like polynitrogen of ZrN10 decomposes into a more stable chain-like polynitrogen structure under the influence of temperature. Additionally, the novel honeycomb-like band-shaped N10 structure hcb-N10 has been discovered by removing the Zr atoms. The absence of the -4 oxidation state in the N10 unit prompts its further polymerization, which makes hcb-N10 possess dynamical and thermal stability in ambient conditions. hcb-N10 is a semiconductor with a bandgap of 2.97 eV due to highly localized electrons. Both chain-ZrN10 and hcb-N10 represent potential candidates for HEDMs with outstanding energy and explosive performance.

7.
Chin J Nat Med ; 22(5): 426-440, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38796216

RESUMO

Chronic intermittent hypoxia (CIH), a principal pathophysiological aspect of obstructive sleep apnea (OSA), is associated with cognitive deficits. Clinical evidence suggests that a combination of Shengmaisan and Liuwei Dihuang Decoctions (SMS-LD) can enhance cognitive function by nourishing yin and strengthening the kidneys. This study aimed to assess the efficacy and underlying mechanisms of SMS-LD in addressing cognitive impairments induced by CIH. We exposed C57BL/6N mice to CIH for five weeks (20%-5% O2, 5 min/cycle, 8 h/day) and administered SMS-LD intragastrically (15.0 or 30 g·kg-1·day) 30 min before each CIH session. Additionally, AG490, a JJanus kinase 2 (JAK2) inhibitor, was administered via intracerebroventricular injection. Cognitive function was evaluated using the Morris water maze, while synaptic and mitochondrial structures were examined by transmission electron microscopy. Oxidative stress levels were determined using DHE staining, and the activation of the erythropoietin (ER)/ER receptor (EPOR)/JAK2 signaling pathway was analyzed through immunohistochemistry and Western blotting. To further investigate molecular mechanisms, HT22 cells were treated in vitro with either SMS-LD medicated serum alone or in combination with AG490 and then exposed to CIH for 48 h. Our results indicate that SMS-LD significantly mitigated CIH-induced cognitive impairments in mice. Specifically, SMS-LD treatment enhanced dendritic spine density, ameliorated mitochondrial dysfunction, reduced oxidative stress, and activated the EPO/EPOR/JAK2 signaling pathway. Conversely, AG490 negated SMS-LD's neuroprotective and cognitive improvement effects under CIH conditions. These findings suggest that SMS-LD's beneficial impact on cognitive impairment and synaptic and mitochondrial integrity under CIH conditions may predominantly be attributed to the activation of the EPO/EPOR/JAK2 signaling pathway.


Assuntos
Disfunção Cognitiva , Medicamentos de Ervas Chinesas , Eritropoetina , Hipóxia , Janus Quinase 2 , Camundongos Endogâmicos C57BL , Transdução de Sinais , Animais , Janus Quinase 2/metabolismo , Medicamentos de Ervas Chinesas/farmacologia , Medicamentos de Ervas Chinesas/administração & dosagem , Camundongos , Transdução de Sinais/efeitos dos fármacos , Disfunção Cognitiva/tratamento farmacológico , Disfunção Cognitiva/etiologia , Masculino , Hipóxia/tratamento farmacológico , Hipóxia/complicações , Receptores da Eritropoetina/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Humanos
8.
Sci Total Environ ; 930: 172755, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38670372

RESUMO

With the advancement of technology, wastewater treatment has become a significant challenge limiting the clean and sustainable development of chemical and metallurgical industries. Foam extraction, based on interfacial separation and mineral flotation, has garnered considerable attention as a wastewater treatment technology due to its unique physicochemical properties. Although considerable excellent accomplishments were reported, there still lacks a comprehensive summary of process features and contaminant removal mechanisms via foam extraction. According to the latest research progresses, the principles and characteristics of foam extraction technology, the classification and application of flotation reagents are systematically summarized in this work. Then comprehensively commented on the application fields and prospects of iterative flotation technology such as ion flotation, adsorption flotation and floating-extraction. The shortcomings and limitations of the current foam extraction technologies were discussed, and the feasible process intensification techniques were highlighted. This review aims to enchance the understanding of the foam extraction mechanism, and provides guidance for the selection appropriate reagents and foam extraction technologies in wastewater treatment.

9.
DNA Res ; 31(3)2024 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-38590243

RESUMO

Calophaca sinica is a rare plant endemic to northern China which belongs to the Fabaceae family and possesses rich nutritional value. To support the preservation of the genetic resources of this plant, we have successfully generated a high-quality genome of C. sinica (1.06 Gb). Notably, transposable elements (TEs) constituted ~73% of the genome, with long terminal repeat retrotransposons (LTR-RTs) dominating this group of elements (~54% of the genome). The average intron length of the C. sinica genome was noticeably longer than what has been observed for closely related species. The expansion of LTR-RTs and elongated introns emerged had the largest influence on the enlarged genome size of C. sinica in comparison to other Fabaceae species. The proliferation of TEs could be explained by certain modes of gene duplication, namely, whole genome duplication (WGD) and dispersed duplication (DSD). Gene family expansion, which was found to enhance genes associated with metabolism, genetic maintenance, and environmental stress resistance, was a result of transposed duplicated genes (TRD) and WGD. The presented genomic analysis sheds light on the genetic architecture of C. sinica, as well as provides a starting point for future evolutionary biology, ecology, and functional genomics studies centred around C. sinica and closely related species.


Assuntos
Genoma de Planta , Retroelementos , Fabaceae/genética , Cromossomos de Plantas , Duplicação Gênica , Tamanho do Genoma , Elementos de DNA Transponíveis , Evolução Molecular , Sequências Repetidas Terminais , Genômica , Íntrons , Filogenia
10.
AMB Express ; 14(1): 42, 2024 Apr 24.
Artigo em Inglês | MEDLINE | ID: mdl-38658521

RESUMO

The unsustainable and widespread utilization of fossil fuels continues to drive the rapid depletion of global supplies. Biodiesel has emerged as one of the most promising alternatives to conventional diesel, leading to growing research interest in its production. Microbes can facilitate the de novo synthesis of a type of biodiesel in the form of fatty acid methyl esters (FAMEs). In this study, Saccharomyces cerevisiae metabolic activity was engineered to facilitate enhanced FAME production. Initially, free fatty acid concentrations were increased by deleting two acetyl-CoA synthetase genes (FAA1, FAA4) and an acyl-CoA oxidase gene (POX1). Intracellular S-adenosylmethionine (SAM) levels were then enhanced via the deletion of an adenosine kinase gene (ADO1) and the overexpression of a SAM synthetase gene (SAM2). Lastly, the S. cerevisiae strain overproducing free fatty acids and SAM were manipulated to express a plasmid encoding the Drosophila melanogaster Juvenile Hormone Acid O-Methyltransferase (DmJHAMT). Using this combination of engineering approaches, a FAME concentration of 5.79 ± 0.56 mg/L was achieved using these cells in the context of shaking flask fermentation. To the best of our knowledge, this is the first detailed study of FAME production in S. cerevisiae. These results will provide a valuable basis for future efforts to engineer S. cerevisiae strains for highly efficient production of biodiesel.

11.
Sci Rep ; 14(1): 9793, 2024 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-38684804

RESUMO

There are many methods to treat keloid, including various excision operations, laser, injection and radiotherapy. However, few studies have explored the effectiveness of single-hole punch excision in keloid treatment. This study aimed to investigate the efficacy and safety of lateral punch excision combined with intralesional steroid injection for keloid treatment through self-control trial. In this self-controlled trial, 50 patients meet the diagnosis of nodular keloid, and try to choose left-right symmetrical control, one skin lesion in the control group (50 skin lesionsin total) and the other in the observation group (50 skin lesions in total).The keloids in the treatment group were initially treated with punch excision combined with intralesional steroid injection, followed by injection treatment alone. Keloids in the control group received intralesional steroid injection alone. The Vancouver Scar Scale (VSS) of the keloid before and after the punch excision was evaluated; the keloid scores at different time points and the number of injection treatments required in both groups were compared, and adverse reactions were observed. The effective rate of the observation group was 86.0%, which was significantly higher than that of the control group (66.0%), and the recurrence rate of 22% was lower than that of the control group (χ2 = 4.141,63417), all of which were statistically significant (all P < 0.05). At the end of treatment, the VSS and total injection times in the observation group were significantly lower than those in the control group (t = 5.900,3.361), with statistical significance (P < 0.01). The combination of single-hole punch excision and intralesional steroid injection is an effective method to treat multiple nodular keloids, shortening the treatment course of tralesional steroid injection without obvious adverse reactions.


Assuntos
Injeções Intralesionais , Queloide , Humanos , Queloide/tratamento farmacológico , Queloide/cirurgia , Queloide/terapia , Injeções Intralesionais/métodos , Feminino , Masculino , Adulto , Resultado do Tratamento , Adulto Jovem , Esteroides/administração & dosagem , Adolescente , Pessoa de Meia-Idade , Terapia Combinada
12.
J Am Chem Soc ; 146(11): 7324-7331, 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38445458

RESUMO

The discovery of superconductivity in twisted bilayer graphene has reignited enthusiasm in the field of flat-band superconductivity. However, important challenges remain, such as constructing a flat-band structure and inducing a superconducting state in materials. Here, we successfully achieved superconductivity in Bi2O2Se by pressure-tuning the flat-band electronic structure. Experimental measurements combined with theoretical calculations reveal that the occurrence of pressure-induced superconductivity at 30 GPa is associated with a flat-band electronic structure near the Fermi level. Moreover, in Bi2O2Se, a van Hove singularity is observed at the Fermi level alongside pronounced Fermi surface nesting. These remarkable features play a crucial role in promoting strong electron-phonon interactions, thus potentially enhancing the superconducting properties of the material. These findings demonstrate that pressure offers a potential experimental strategy for precisely tuning the flat band and achieving superconductivity.

13.
PLoS One ; 19(3): e0296792, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38452099

RESUMO

Chronic intermittent hypoxia (CIH) may play an important role in the development of diabetic cardiomyopathy (DCM). However, the exact mechanism of CIH-induced myocardial injury in DCM remains unclear. In vivo, the db/db mice exposed to CIH were established, and in vitro, the H9C2 cells were exposed to high glucose (HG) combined with intermittent hypoxia (IH). The body weight (BW), fasting blood glucose (FBG) and food intake were measured every two weeks. The glycolipid metabolism was assessed with the oral glucose tolerance test (OGTT) and insulin resistance (IR). Cardiac function was detected by echocardiography. Cardiac pathology was detected by HE staining, Masson staining, and transmission electron microscopy. The level of reactive oxygen species (ROS) in myocardial tissue was detected by dihydroethidium (DHE). The apoptosis was detected by TUNEL staining. The cell viability, ROS, and the mitochondrial membrane potential were detected by the cell counting kit-8 (CCK-8) assay and related kits. Western blotting was used to analyze the liver kinase B1/AMP-activated protein kinase/ nuclear factor-erythroid 2-related factor 2 (LKB1/AMPK/Nrf2) signaling pathway. CIH exposure accelerated glycolipid metabolism disorders and cardiac injury, and increased the level of cardiac oxidative stress and the number of positive apoptotic cells in db/db mice. IH and HG decreased the cell viability and the level of mitochondrial membrane potential, and increased ROS expression in H9C2 cells. These findings indicate that CIH exposure promotes glycolipid metabolism disorders and myocardial apoptosis, aggravating myocardial injury via the LKB1/AMPK/Nrf2 pathway in vitro and in vivo.


Assuntos
Diabetes Mellitus , Cardiomiopatias Diabéticas , Camundongos , Animais , Espécies Reativas de Oxigênio/metabolismo , Proteínas Quinases Ativadas por AMP/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Hipóxia/metabolismo , Transdução de Sinais , Apoptose , Glicolipídeos
15.
Artigo em Inglês | MEDLINE | ID: mdl-38393582

RESUMO

Xylitol is a polyol widely used in food, pharmaceuticals, and light industries. It is currently produced through the chemical catalytic hydrogenation of xylose and generates xylose mother liquor as a substantial byproduct in the procedure of xylose extraction. If xylose mother liquor could also be efficiently bioconverted to xylitol, the greenness and atom economy of xylitol production would be largely improved. However, xylose mother liquor contains a mixture of glucose, xylose, and arabinose, raising the issue of carbon catabolic repression in its utilization by microbial conversion. Targeting this challenge, the transcriptional activator XylR was overexpressed in a previously constructed xylitol-producing E. coli strain CPH. The resulting strain CPHR produced 16.61 g/L of xylitol in shake-flask cultures from the mixture of corn cob hydrolysate and xylose mother liquor (1:1, v/v) with a xylose conversion rate of 90.1%, which were 2.23 and 2.15 times higher than the starting strain, respectively. Furthermore, XylR overexpression upregulated the expression levels of xylE, xylF, xylG, and xylH genes by 2.08-2.72 times in arabinose-containing medium, suggesting the alleviation of transcriptional repression of xylose transport genes by arabinose. This work lays the foundation for xylitol bioproduction from xylose mother liquor.

16.
Chemosphere ; 353: 141533, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38403126

RESUMO

Ion precipitation flotation technology was demonstrated to be an efficient method for the separation of valuable metals from low-concentration solution. However, the selective separation of three metals from mixing solution is a great challenge, and highly selective reagents are the key to polymetallic separation. In this work, stepwise separation of Co and Zn from the simulated zinc hydrometallurgy wastewater containing ternary Co-Zn-Mn metals by ion precipitation flotation process was proposed. It's demonstrated that organic reagents of 1-nitroso-2-naphthol (NN) and sodium dimethyldithiocarbamate (SDDC) had excellent selectivity for the capture of Co and Zn to form respective precipitate from wastewaters via the chelation reactions. After precipitation, dodecylpyridinium chloride (DPC) and tetradecyltrimethylammonium bromide (TTAB) were chosen as surfactants for the separation of Co and Zn sediments from the solution via the flotation process. The effects of solution pH, molar ratio, reaction temperature, and reaction time on the selective precipitation efficiencies of Co and Zn as well as the effects of surfactant dosage and flotation gas velocity on the flotation separation efficiencies were systematically investigated. It's demonstrated that the comprehensive recovery rates of Co, Mn, and Zn reach 98%, 90%, and 99%, respectively. After separation, oxidation calcination of the foam products was conducted to prepare high-purity Co3O4 and ZnO nanoparticles in which the organic matters were burnt out with gas emissions. The stepwise chelation capture mechanisms of Co and Zn by highly selective precipitation reagents were minutely discussed. It's demonstrated that the proposed selective stepwise precipitation and flotation method is suitable for recovery of critical metal ions from low-concentration polymetallic wastewaters.


Assuntos
Águas Residuárias , Zinco , Metais , Indicadores e Reagentes , Tensoativos , Íons
17.
J Phys Chem Lett ; 15(8): 2233-2240, 2024 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-38377180

RESUMO

Microstructure transformation of materials under compression is crucial to understanding their high-pressure phase transformation. However, direct observation of the microstructure of compressive materials is a considerable challenge, which impedes the understanding of the relations among phase transformation, microstructure, and material properties. In this study, we used transmission Kikuchi diffraction and transmission electron microscopy to intuitively characterize pressure-induced phase transformation and microstructure of TiO2. We observed the changes of twin boundaries with increasing pressure and intermediate phase TiO2-I of anatase transformed into TiO2-II (α-PbO2 phase) for the first time. The following changes occur during this transformation: anatase (diameter of ∼100 nm) → anatase twins 60° along the [110] zone axis → intermediate TiO2-I twins 60° along the [010] zone axis → TiO2-II twins 90° along the [010] zone axis. These results directly reveal the crystallographic relation among these structures, enhancing our understanding of the phase transformation in TiO2 nanocrystals.

18.
Proc Natl Acad Sci U S A ; 121(9): e2316580121, 2024 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-38377204

RESUMO

Achieving high-performance materials with superior mechanical properties and electrical conductivity, especially in large-sized bulk forms, has always been the goal. However, it remains a grand challenge due to the inherent trade-off between these properties. Herein, by employing nanodiamonds as precursors, centimeter-sized diamond/graphene composites were synthesized under moderate pressure and temperature conditions (12 GPa and 1,300 to 1,500 °C), and the composites consisted of ultrafine diamond grains and few-layer graphene domains interconnected through covalently bonded interfaces. The composites exhibit a remarkable electrical conductivity of 2.0 × 104 S m-1 at room temperature, a Vickers hardness of up to ~55.8 GPa, and a toughness of 10.8 to 19.8 MPa m1/2. Theoretical calculations indicate that the transformation energy barrier for the graphitization of diamond surface is lower than that for diamond growth directly from conventional sp2 carbon materials, allowing the synthesis of such diamond composites under mild conditions. The above results pave the way for realizing large-sized diamond-based materials with ultrahigh electrical conductivity and superior mechanical properties simultaneously under moderate synthesis conditions, which will facilitate their large-scale applications in a variety of fields.

19.
ACS Appl Mater Interfaces ; 16(3): 3605-3620, 2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38207161

RESUMO

Simultaneous study of magnetic and electrocatalytic properties of cobaltites under extreme conditions expands the understanding of physical and chemical processes proceeding in them with the possibility of their further practical application. Therefore, La0.6Sr0.4CoO3 (LSCO) nanopowders were synthesized at different annealing temperatures tann = 850-900 °C, and their multifunctional properties were studied comprehensively. As tann increases, the rhombohedral perovskite structure of the LSCO becomes more single-phase, whereas the average particle size and dispersion grow. Co3+ and Co4+ are the major components. It has been found that LSCO-900 shows two main Curie temperatures, TC1 and TC2, associated with a particle size distribution. As pressure P increases, average ⟨TC1⟩ and ⟨TC2⟩ increase from 253 and 175 K under ambient pressure to 268 and 180 K under P = 0.8 GPa, respectively. The increment of ⟨dTC/dP⟩ for the smaller and bigger particles is sufficiently high and equals 10 and 13 K/GPa, respectively. The magnetocaloric effect in the LSCO-900 nanopowder demonstrates an extremely wide peak δTfwhm > 50 K that can be used as one of the composite components, expanding its working temperature window. Moreover, all LSCO samples showed excellent electrocatalytic performance for the oxygen evolution reaction (OER) process (overpotentials of only 265-285 mV at a current density of 10 mA cm-2) with minimal η10 for LSCO-900. Based on the experimental data, it was concluded that the formation of a dense amorphous layer on the surface of the particles ensures high stability as a catalyst (at least 24 h) during electrolysis in 1 M KOH electrolyte.

20.
Ultrason Sonochem ; 102: 106758, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38219552

RESUMO

Clean and efficient extraction and separation of precious metals from discarded Pb-Sn alloy is critical to the sustainable utilization of solid waste resources. Dense oxide layer and compact alloy texture in the waste Pb-Sn alloy pose challenges to the effective leaching process. Ultrasonic waves are demonstrated to improve separation efficiency via the favorable physical and chemical effects in solution system. In this study, ultrasound-assisted leaching technology is attempted to rapidly and selectively extract Pb from the waste Pb-Sn alloy, and gives emphasis on ultrasonic electrochemical behaviors. The Eh-pH diagrams of Sn-H2O and Pb-H2O systems were firstly analyzed to lay the selective dissolution foundation. It's indicated that oxidizing HNO3 lixiviant is suitable to realize the selective separation of Pb. Both Sn and Pb can be dissolved to ionic Sn2+ and Pb2+ in the HNO3 solution. However, Sn2+ rapidly oxidizes to Sn4+ and Sn4+ further hydrolyzes to insoluble SnO2, which will agglomerate on unreacted materials to limit internal metal leaching in conventional leaching process. Due to the vibratory stripping of oxide layer by physical effect of ultrasound, the conventional acid leaching time for Pb extraction can be halved with the ultrasound assistance. About 99.12 % Pb and only 0.1 % Sn are dissolved in ultrasound-assisted leaching under the following optimal parameters: 0.5 mol/L HNO3, leaching temperature of 80 °C, time of 30 min, liquid-to-solid ratio of 20 mL/g, and ultrasound intensity of 0.52 W/cm2. Leaching kinetics of Pb, phase transition, microstructure evolution, Pb-Sn galvanic corrosion and dissolution polarization curve were studied to determine the ultrasonic enhanced dissolution mechanism. Notably, Pb and Sn form a microcorrosion galvanic cell in which Sn acts as a cathode and is protected while the Pb undergoes intensifying corrosion as the anode giving rise to the higher Pb dissolution efficiency. Eventually, it's suggested that Pb can be rapidly extracted and separated from the waste Pb-Sn alloy during the ultrasound-assisted HNO3 leaching process via the ultrasound physical and chemical effects, especially the sonochemistry aspect of intensified spot corrosion and galvanic corrosion. The proposed ultrasonic electrochemical corrosion in this work were applicable to the extraction of valuable metals from various waste alloys through leaching method.

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