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1.
Ecotoxicol Environ Saf ; 280: 116525, 2024 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-38852468

RESUMEN

Air pollution is widely acknowledged as a significant risk factor for human health, especially reproductive health. Nevertheless, many studies have disregarded the potentially mixed effects of air pollutants on reproductive outcomes. We performed a retrospective cohort study involving 8048 women with 9445 cycles undergoing In Vitro Fertilization (IVF) and Intracytoplasmic Sperm Injection (ICSI) in China, from 2017 to 2021. A land-use random forest model was applied to estimate daily residential exposure to air pollutants, including sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), ozone (O3), and fine particulate matter (PM2.5). Individual and joint associations between air pollutants and oocyte-related outcomes of ART were evaluated. In 90 days prior to oocyte pick-up to oocyte pick-up (period A), NO2, O3 and CO was negatively associated with total oocyte yield. In the 90 days prior to oocyte pick-up to start of gonadotropin medication (Gn start, period B), there was a negative dose-dependent association of exposure to five air pollutants with total oocyte yield and mature oocyte yield. In Qgcomp analysis, increasing the multiple air pollutants mixtures by one quartile was related to reducing the number of oocyte pick-ups by -2.00 % (95 %CI: -2.78 %, -1.22 %) in period A, -2.62 % (95 %CI: -3.40 %, -1.84 %) in period B, and -0.98 % (95 %CI: -1.75 %, -0.21 %) in period C. During period B, a 1-unit increase in the WQS index of multiple air pollutants exposure was associated with fewer number of total oocyte (-1.27 %, 95 %CI: -2.16 %, -0.36 %) and mature oocyte (-1.42 %, 95 %CI: -2.41 %, -0.43 %). O3 and NO2 were major contributors with adverse effects on the mixed associations. Additionally, period B appears to be the susceptible window. Our study implies that exposure to air pollution adversely affects oocyte-related outcomes, which raises concerns about the potential adverse impact of air pollution on women's reproductive health.


Asunto(s)
Contaminantes Atmosféricos , Oocitos , Femenino , Humanos , Contaminantes Atmosféricos/toxicidad , Contaminantes Atmosféricos/análisis , Estudios Retrospectivos , Oocitos/efectos de los fármacos , Adulto , China , Técnicas Reproductivas Asistidas , Contaminación del Aire/efectos adversos , Ozono , Material Particulado/toxicidad , Material Particulado/análisis , Exposición a Riesgos Ambientales/efectos adversos , Fertilización In Vitro , Estudios de Cohortes , Dióxido de Nitrógeno/análisis
2.
Nat Commun ; 15(1): 4407, 2024 May 23.
Artículo en Inglés | MEDLINE | ID: mdl-38782885

RESUMEN

Topological flat bands - where the kinetic energy of electrons is quenched - provide a platform for investigating the topological properties of correlated systems. Here, we report the observation of a topological flat band formed by polar-distortion-assisted Rashba splitting in the three-dimensional Dirac material ZrTe5. The polar distortion and resulting Rashba splitting on the band are directly detected by torque magnetometry and the anomalous Hall effect, respectively. The local symmetry breaking further flattens the band, on which we observe resistance oscillations beyond the quantum limit. These oscillations follow the temperature dependence of the Lifshitz-Kosevich formula but are evenly distributed in B instead of 1/B at high magnetic fields. Furthermore, the cyclotron mass gets anomalously enhanced about 102 times at fields ~ 20 T. Our results provide an intrinsic platform without invoking moiré or order-stacking engineering, which opens the door for studying topologically correlated phenomena beyond two dimensions.

3.
Nano Lett ; 24(17): 5125-5131, 2024 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-38639405

RESUMEN

We report a study of thickness-dependent interband and intraband magnetic breakdown by thermoelectric quantum oscillations in ZrSiSe nanoplates. Under high magnetic fields of up to 30 T, quantum oscillations arising from degenerated hole pockets were observed in thick ZrSiSe nanoplates. However, when decreasing the thickness, plentiful multifrequency quantum oscillations originating from hole and electron pockets are captured. These multiple frequencies can be explained by the emergent interband magnetic breakdown enclosing individual hole and electron pockets and intraband magnetic breakdown within spin-orbit coupling (SOC) induced saddle-shaped electron pockets, resulting in the enhanced contribution to thermal transport in thin ZrSiSe nanoplates. These experimental frequencies agree well with theoretical calculations of the intriguing tunneling processes. Our results introduce a new member of magnetic breakdown to the field and open up a dimension for modulating magnetic breakdown, which holds fundamental significance for both low-dimensional topological materials and the physics of magnetic breakdown.

4.
Food Chem ; 447: 138975, 2024 Jul 30.
Artículo en Inglés | MEDLINE | ID: mdl-38489882

RESUMEN

Here, the influence and potential mechanism by which cellulose nanocrystals (CNC) collaborated with Ca2+ enhancing the heat-induced gelation of pea protein isolate (PPI) were investigated. It was found that the combination of 0.45% CNC and 15 mM Ca2+ synergistically increased the gel strength (from 14.18 to 65.42 g) and viscoelasticity of PPI while decreased the water holding capacity. The improved particle size, turbidity, and thermostability as well as the reduced solubility, crystallinity, and gel porosity were observed in CNC/CaCl2 composite system. CNC fragments bind to specific amino acids in 11S legumin and 7S vicilin mainly through hydrogen bonding and van der Waals forces. Moreover, changes in the protein secondary structure and enhancement of the molecular interaction induced by CNC and Ca2+ could favor the robust gel network. The results will provide a new perspective on the functional regulation of pea protein and the creation of pea protein gel-based food.


Asunto(s)
Nanopartículas , Proteínas de Guisantes , Celulosa/química , Calcio , Geles/química , Agua/química , Nanopartículas/química
5.
J Colloid Interface Sci ; 663: 295-308, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38402824

RESUMEN

Developing innovative surface-enhanced Raman scattering (SERS) nanotags continues to attract significant attention due to their unparalleled sensitivity and specificity for in vitro diagnostic and in vivo tumor imaging applications. Here, we report a new class of bright and stable SERS nanotags using alkylmercaptan-PEG (AMP) polymers. Due to its amphiphilic structure and a thiol anchoring group, these polymers strongly absorb onto gold nanoparticles, leading to an inner hydrophobic layer and an outer hydrophilic PEG layer. The inner hydrophobic layer serves to "lock in" the Raman reporter molecules adsorbed on the particle surface via favorable hydrophobic interactions that also allow denser PEG coatings, which "lock out" other molecules from competitive binding or adsorbing to the gold surface, thereby providing superior colloidal and signal stability. The higher grafting densities of AMP polymers compared to conventional thiolated PEG also led to dramatic increases in cellular target selectivity, with specific-to-nonspecific binding ratios reaching beyond an order of magnitude difference. Experimental evaluations and theoretical considerations of dielectric polarization and light scattering indicate that the hydrophobic layer provides a more favorable dielectric environment with less plasmon dampening, greater particle scattering efficiency, and increased Raman reporter polarizability. Accordingly, SERS nanotags with AMP polymer coatings are observed to be considerably brighter (∼10-fold). Furthermore, the AMP-coated SERS nanotag's increased intensity and avidity can boost cellular detection sensitivity by nearly two orders of magnitude.


Asunto(s)
Nanopartículas del Metal , Nanopartículas del Metal/química , Oro/química , Espectrometría Raman/métodos , Línea Celular Tumoral , Polímeros
6.
Plant Sci ; 339: 111930, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38007196

RESUMEN

Switchgrass (Panicum virgatum L.) plays a pivotal role as a bioenergy feedstock in the production of cellulosic ethanol and contributes significantly to enhancing ecological grasslands and soil quality. The utilization of non-coding RNAs (ncRNAs) has gained momentum in deciphering the intricate genetic responses to abiotic stress in various plant species. Nevertheless, the current research landscape lacks a comprehensive exploration of the responses of diverse ncRNAs, including long non-coding RNAs (lncRNAs), circular RNAs (circRNAs), and microRNAs (miRNAs), to drought stress in switchgrass. In this study, we employed whole transcriptome sequencing to comprehensively characterize the expression profiles of both mRNA and ncRNAs during episodes of drought stress in switchgrass. Our analysis identified a total of 12,511 mRNAs, 59 miRNAs, 38 circRNAs, and 368 lncRNAs that exhibited significant differential expression between normal and drought-treated switchgrass leaves. Notably, the majority of up-regulated mRNAs displayed pronounced enrichment within the starch and sucrose metabolism pathway, as validated through KEGG analysis. Co-expression analysis illuminated that differentially expressed (DE) lncRNAs conceivably regulated 1308 protein-coding genes in trans and 7110 protein-coding genes in cis. Furthermore, both cis- and trans-target mRNAs of DE lncRNAs exhibited enrichment in four common KEGG pathways. The intricate interplay between lncRNAs and circRNAs with miRNAs via miRNA response elements was explored within the competitive endogenous RNA (ceRNA) network framework. As a result, we constructed elaborate regulatory networks, including lncRNA-novel_miRNA480-mRNA, lncRNA-novel_miRNA304-mRNA, lncRNA/circRNA-novel_miRNA122-PvSS4, and lncRNA/circRNA-novel_miRNA14-PvSS4, and subsequently validated the functionality of the target gene, starch synthase 4 (PvSS4). Furthermore, through the overexpression of PvSS4, we ascertained its capacity to enhance drought tolerance in yeast. However, it is noteworthy that PvSS4 did not exhibit any discernible impact under salt stress conditions. These findings, as presented herein, not only contribute substantively to our understanding of ceRNA networks but also offer a basis for further investigations into their potential functions in response to drought stress in switchgrass.


Asunto(s)
MicroARNs , Panicum , ARN Largo no Codificante , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN Circular/genética , ARN Circular/metabolismo , Panicum/genética , Panicum/metabolismo , ARN Largo no Codificante/genética , Sequías , Perfilación de la Expresión Génica , MicroARNs/genética , MicroARNs/metabolismo , Redes Reguladoras de Genes
7.
Natl Sci Rev ; 11(1): nwad107, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38116091

RESUMEN

As compressed hydrides constantly refresh the records of superconducting critical temperatures (Tc) in the vicinity of room temperature, this further reinforces the confidence to find more high-temperature superconducting hydrides. In this process, metastable phases of superhydrides offer enough possibilities to access superior superconducting properties. Here we report a metastable hexagonal lanthanum superhydride (P63/mmc-LaH10) stabilized at 146 GPa by introducing an appropriate proportion of Al, which exhibits high-temperature superconductivity with Tc ∼ 178 K, and this value is enhanced to a maximum Tc ∼ 223 K at 164 GPa. A huge upper critical magnetic field value Hc2(0) reaches 223 T at 146 GPa. The small volume expansion of P63/mmc-(La, Al) H10 compared with the binary LaH10 indicates the possible interstitial sites of Al atoms filling into the La-H lattice, instead of forming conventional ternary alloy-based superhydrides. This work provides a new strategy for metastable high-temperature superconductors through the multiple-element system.

8.
J Environ Manage ; 348: 119462, 2023 Dec 15.
Artículo en Inglés | MEDLINE | ID: mdl-37925986

RESUMEN

BACKGROUND: Humans are exposed to various chemicals, including organophosphate esters (OPEs), phthalates (PAEs), and phenols. The effects on early reproductive outcomes of in vitro fertilization (IVF) remain unclear. METHODS: We recruited 192 women and 157 men who underwent IVF treatment. A total of forty-nine urinary chemicals were detected, including six OPEs, fifteen PAEs, six parabens, two chlorophenols, nine bisphenols, five benzophenones, and six synthetic phenolic antioxidants. We examined the individual and joint effects of parental chemical exposure on early reproductive outcomes. RESULTS: We found that certain chemicals were associated with early reproductive outcomes in Poisson regression models. For example, urinary diphenyl phosphate was negatively associated with high-quality embryos in both female (ß: -0.12, 95%CI: -0.17, -0.07) and male partners (ß: -0.09, 95%CI: -0.15, -0.03). A negative association was found between mixed chemicals and high-quality embryos in Bayesian kernel machine regression, weighted quantile sum regression (ß: -0.34, 95%CI: -0.60, -0.07), and quantile-based g-computation model (ß: -0.69, 95%CI: -1.34, -0.05) among female partners. Paternal mixture exposure was not associated with early reproductive outcomes. CONCLUSIONS: Our results indicated that increased exposure to environmental chemicals was associated with adverse early reproductive outcomes of IVF, especially female partners.


Asunto(s)
Contaminantes Ambientales , Exposición Materna , Humanos , Masculino , Femenino , Teorema de Bayes , Reproducción , Fertilización In Vitro , Fenoles , Organofosfatos , Exposición a Riesgos Ambientales
9.
Nano Lett ; 23(19): 9026-9033, 2023 Oct 11.
Artículo en Inglés | MEDLINE | ID: mdl-37767914

RESUMEN

The quantum Hall effect is one of the exclusive properties displayed by Dirac Fermions in topological insulators, which propagates along the chiral edge state and gives rise to quantized electron transport. However, the quantum Hall effect formed by the nondegenerate Dirac surface states has been elusive so far. Here, we demonstrate the nondegenerate integer quantum Hall effect from the topological surface states in three-dimensional (3D) topological insulator ß-Ag2Te nanostructures. Surface-state dominant conductance renders quantum Hall conductance plateaus with a step of e2/h, along with typical thermopower behaviors of two-dimensional (2D) massless Dirac electrons. The 2D nature of the topological surface states is proven by the electrical and thermal transport responses under tilted magnetic fields. Moreover, the degeneracy of the surface states is removed by structure inversion asymmetry (SIA). The evidenced SIA-induced nondegenerate integer quantum Hall effect in low-symmetry ß-Ag2Te has implications for both fundamental study and the realization of topological magneto-electric effects.

10.
Carbohydr Polym ; 319: 121181, 2023 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-37567717

RESUMEN

The current serious environmental problems have greatly encouraged the design and development of food packaging materials with environmental protection, green, and safety. This study aims to explore the synergistic effect and corresponding mechanism of cellulose nanocrystals (CNC) and CaCl2 to enhance the film-forming properties of pea protein isolate (PPI). The combination of 0.5 % CNC and 4.5 mM CaCl2 resulted in a 76.6 % increase in tensile strength when compared with pure PPI-based film. Meanwhile, this combination effectively improved the barrier performance, surface hydrophobicity, water resistance, and biodegradability of PPI-based film. The greater crystallinity, viscoelasticity, lower water mobility, and improved protein spatial conformation were also observed in CNC/CaCl2 composite film. Compared with the control, the main degradation temperature of composite film was increased from 326.23 °C to 335.43 °C. The CNC chains bonded with amino acid residue of pea protein at specific sites via non-covalent forces (e.g., hydrogen bonds, Van der Waals forces). Meanwhile, Ca2+ promoted the ordered protein aggregation at suitable rate and degree, accompanied by the formation of more disulfide bonds. Furthermore, proper Ca2+ could strengthen the cross-linking and interaction between CNC and protein, thereby establishing a stable network structure. The prepared composite films are expected to be used for strawberry preservation.


Asunto(s)
Nanopartículas , Proteínas de Guisantes , Celulosa/química , Calcio , Cloruro de Calcio , Agua/química , Nanopartículas/química
11.
Front Cell Dev Biol ; 11: 1204017, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37377732

RESUMEN

Fertilization is a complex and highly regulated process that involves a series of molecular interactions between sperm and oocytes. However, the mechanisms of proteins involved in human fertilization, such as that of testis-specific SPACA4, remain poorly understood. Here we demonstrated that SPACA4 is a spermatogenic cell-specific protein. SPACA4 is expressed during spermatogenesis, upregulated in early-stage spermatids, and downregulated in elongating spermatids. SPACA4 is an intracellular protein that locates in the acrosome and is lost during the acrosome reaction. Incubation with antibodies against SPACA4 inhibited the binding of spermatozoa to zona pellucida. SPACA4 protein expression levels across different semen parameters were similar but varied significantly among patients. A prospective clinical study found no association between SPACA4 protein levels and fertilization or cleavage rates. Thus, the study suggests a novel function for SPACA4 in human fertilization in a non-dose-dependent manner. However, a larger clinical trial is required to evaluate the potential use of sperm SPACA4 protein levels to predict fertilization potential.

12.
Carbohydr Polym ; 314: 120940, 2023 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-37173023

RESUMEN

This work focused on the pathways by which NCC regulated the digestibility of corn starch. The addition of NCC changed the viscosity of the starch during pasting, improved the rheological properties and short-range order of the starch gel, and finally formed a compact, ordered, and stable gel structure. In this respect, NCC affected the digestion process by changing the properties of the substrate, which reduced the degree and rate of starch digestion. Moreover, NCC induced changes in the intrinsic fluorescence, secondary conformation, and hydrophobicity of α-amylase, which lowered its activity. Molecular simulation analyses suggested that NCC bonded with amino acid residues (Trp 58, Trp 59, and Tyr 62) at the active site entrance via hydrogen bonding and van der Waals forces. In conclusion, NCC decreased CS digestibility by modifying the gelatinization and structural properties of starch and inhibiting α-amylase activity. This study provides new insights into the mechanisms by which NCC regulates starch digestibility, which could be beneficial for the development of functional foods to tackle type 2 diabetes.


Asunto(s)
Diabetes Mellitus Tipo 2 , Almidón , Almidón/química , Celulosa/química , Zea mays/química , Digestión , alfa-Amilasas
13.
Environ Geochem Health ; 45(10): 7199-7214, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37258900

RESUMEN

To assess the pollution characteristics and health risks associated with street dust exposure among preschool children in typical industrial and mining areas, we analyzed heavy metal concentrations of 20 urban street dusts in commercial area (CA), residential area (RA), scientific and educational area (SEA) and industrial and mining area (IMA) from Baiyin, NW China. The average concentrations of Cr, Mn, Ni, Cu, Zn, Cd, Pb, As and Hg were 614.96, 484.25, 1757.74, 6868.86, 893.19, 77.62, 1473.99, 15.01 and 0.59 mg·kg-1, respectively. The ecological risk indexes for Cd, Cu and Hg were found as 20,075.20, 1425.07 and 1174.86, respectively, and the ecological risk was extremely high. The pollution load indexes (PLI) were > 1 for all four functional areas. The total hazard index (THI) for different functional areas were more than 1, and the main exposure pathway for children was ingestion route. Heavy metals in street dust of the IMA had the highest THI for children (43.88), and HI of Pb was being most significant (17.38). In addition, the carcinogenic risk to children via the respiratory route was acceptable. Furthermore, factor analysis and cluster analysis classified heavy metals into two groups, indicating common anthropogenic sources for Cr, Ni, Cu, Zn, Cd, Pb, As and Hg. In conclusion, urban street dusts from industrial and mining area of Baiyin, NW China were found polluted by heavy metals and the pollution would pose an obvious non-carcinogenic risk to preschool children.


Asunto(s)
Mercurio , Metales Pesados , Preescolar , Humanos , Polvo/análisis , Cadmio/análisis , Monitoreo del Ambiente , Plomo/análisis , Metales Pesados/análisis , Mercurio/análisis , Ciudades , China , Carcinógenos/análisis , Medición de Riesgo
14.
Plant Cell Rep ; 42(4): 735-748, 2023 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-36806743

RESUMEN

KEY MESSAGE: PvLBD12 enhanced the salt tolerance by increasing proline accumulation, improving K+ accumulation, and decreasing reactive oxygen species level in switchgrass. Abiotic stresses are the serious factors which limit plant development and productivity and restrict the agricultural economy. It is important, therefore, to understand the mechanism of abiotic tolerance in plants. Lateral organ boundaries domain (LBD) proteins as plant-specific transcription factors play important function in plant lateral organ development, plant regeneration, and abiotic stress. In our study, we identify 69 LBD members from switchgrass genome-wide sequences and classify them based on their homology with LBD proteins in Arabidopsis. RT-qPCR showed that PvLBD genes had different expression patterns under abiotic stress conditions, indicating that they play important roles in various stress. PvLBD12 was selected as a candidate gene for further functional analysis because it had the highest expression level under salt stress. Overexpression of PvLBD12 enhanced salt tolerance by altering a wide range of physiological responses (like increased proline accumulation, reduced malondialdehyde production, improved K+ accumulation, and reduced Na+ absorption) in switchgrass. Some stress response genes such as proline biosynthesis gene PvP5CS1, vacuolar Na+(K+)/H+ antiporter gene PvNHX1, two key ROS-scavenging enzyme genes PvCAT and PvSOD were all upregulated in PvLBD12 overexpression lines. Taken together, PvLBD12 plays a pivotal role in response to salt stress by increasing proline accumulation, improving K+ accumulation, reducing Na+ absorption, and decreasing reactive oxygen species level. It will be better to understand the potential biological functions of LBD genes in other plants.


Asunto(s)
Arabidopsis , Panicum , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Panicum/genética , Panicum/metabolismo , Plantas Modificadas Genéticamente/genética , Plantas Modificadas Genéticamente/metabolismo , Tolerancia a la Sal/genética , Especies Reactivas de Oxígeno/metabolismo , Arabidopsis/metabolismo , Prolina/metabolismo , Estrés Fisiológico/genética , Regulación de la Expresión Génica de las Plantas , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo
15.
Environ Sci Pollut Res Int ; 30(6): 14190-14199, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36151434

RESUMEN

One of the ways to fight against global warming is by means of green technological progress. This paper explores the nonlinear relationship between R&D investment and green technological progress based on panel threshold regression model using panel data of 26 manufacturing sub-sectors in China from 2004 to 2017. The results show that the double-threshold model can better explain the nonlinear relationship between the two, and the R&D investment in the three ranges of low, medium, and high levels can significantly promote green technological progress in China's manufacturing industry. However, with the improvement of R&D investment level, the promotion effect of R&D investment on the progress of manufacturing green technology is decreasing, which explains the low R&D intensity of China's manufacturing industry to a certain extent. When the level of R&D investment reaches a certain level, its promoting effect on manufacturing industry's green technological progress will be greatly reduced, and the motivation of enterprises to invest in R&D based on self-interest will decrease, so that the scale of R&D investment will be lower than the optimal scale of society. R&D investment can also improve green technical efficiency change. In addition, environmental regulation can promote green technological progress in manufacturing industry. However, due to the implementation of output-oriented environmental regulation policies, China's environmental regulation can inhibit the improvement of green technical efficiency change. Based on the conclusion, this paper argues that China should implement differentiated R&D subsidy policies for manufacturing enterprises, especially to increase R&D subsidies for enterprises with a medium level of R&D investment, and formulate appropriate environmental regulatory policies, to promote green and low-carbon transformation of China's manufacturing sector.


Asunto(s)
Comercio , Industrias , Industria Manufacturera , Tecnología , China , Desarrollo Económico
16.
Sensors (Basel) ; 22(24)2022 Dec 16.
Artículo en Inglés | MEDLINE | ID: mdl-36560307

RESUMEN

This paper presents a straightforward method to develop a nanoporous graphene oxide (NGO)-functionalized quartz crystal microbalance (QCM) gas sensor for the detection of trimethylamine (TMA), aiming to form a reliable monitoring mechanism strategy for low-concentration TMA that can still cause serious odor nuisance. The synthesized NGO material was characterized by transmission electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy to verify its structure and morphology. Compared with the bare and GO-based QCM sensors, the NGO-based QCM sensor exhibited ultra-high sensitivity (65.23 Hz/µL), excellent linearity (R2 = 0.98), high response/recovery capability (3 s/20 s) and excellent repeatability (RSD = 0.02, n = 3) toward TMA with frequency shift and resistance. Furthermore, the selectivity of the proposed NGO-based sensor to TMA was verified by analysis of the dual-signal responses. It is also proved that increasing the conductivity did not improve the resistance signal. This work confirms that the proposed NGO-based sensor with dual signals provides a new avenue for TMA sensing, and the sensor is expected to become a potential candidate for gas detection.


Asunto(s)
Grafito , Nanoporos , Tecnicas de Microbalanza del Cristal de Cuarzo , Grafito/química , Cuarzo
17.
Natl Sci Rev ; 9(10): nwab208, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-36380858

RESUMEN

The interplay of electron correlations and topological phases gives rise to various exotic phenomena including fractionalization, excitonic instability and axionic excitation. Recently discovered transition-metal pentatellurides can reach the ultra-quantum limit in low magnetic fields and serve as good candidates for achieving such a combination. Here, we report evidence of density wave and metal-insulator transition in HfTe5 induced by intense magnetic fields. Using the non-linear transport technique, we detect a distinct non-linear conduction behavior in the longitudinal resistivity within the a-c plane, corresponding to the formation of a density wave induced by magnetic fields. In high fields, the onset of non-linear conduction in the Hall resistivity indicates an impurity-pinned magnetic freeze-out as the possible origin of the insulating behavior. These frozen electrons can be gradually reactivated into mobile states above a threshold of electric field. This experimental evidence calls for further investigation into the underlying mechanism of the bulk quantum Hall effect and field-induced phase transitions in pentatellurides.

18.
Acta Biomater ; 153: 159-177, 2022 11.
Artículo en Inglés | MEDLINE | ID: mdl-36152907

RESUMEN

Injectable hydrogels based on various functional biocompatible materials have made rapid progress in the field of bone repair. In this study, a self-healing and injectable polysaccharide-based hydrogel was prepared for bone tissue engineering. The hydrogel was made of carboxymethyl chitosan (CMCS) and calcium pre-cross-linked oxidized gellan gum (OGG) cross-linked by the Schiff-base reaction. Meanwhile, magnetic hydroxyapatite/gelatin microspheres (MHGMs) were prepared by the emulsion cross-linking method. The antibacterial drugs, tetracycline hydrochloride (TH) and silver sulfadiazine (AgSD), were embedded into the MHGMs. To improve the mechanical and biological properties of the hydrogels, composite hydrogels were prepared by compounding hydroxyapatite (HAp) and drug-embedded MHGMs. The physical, chemical, mechanical and rheological properties of the composite hydrogels were characterized, as well as in vitro antibacterial tests and biocompatibility assays, respectively. Our results showed that the composite hydrogel with 6% (w/v) HAp and 10 mg/mL MHGMs exhibited good magnetic responsiveness, self-healing and injectability. Compared with the pure hydrogel, the composite hydrogel showed a 38.8% reduction in gelation time (196 to 120 s), a 65.6% decrease in swelling rate (39.4 to 13.6), a 51.9% increase in mass residual after degradation (79.5 to 120.8%), and a 143.7% increase in maximum compressive stress (53.6 to 130.6 KPa). In addition, this composite hydrogel showed good drug retardation properties and antibacterial effects against both S. aureus and E. coli. CCK-8 assay showed that composite hydrogel maintained high cell viability (> 87%) and rapid cell proliferation after 3 days, indicating that this smart hydrogel is expected to be an alternative scaffold for drug delivery and bone regeneration. STATEMENT OF SIGNIFICANCE: Biopolymer hydrogels have been considered as the promising materials for the treatment of tissue engineering and drug delivery. Injectable hydrogels with and self-healing properties and responsiveness to external stimuli have been extensively investigated as cell scaffolds and bone defects, due to their diversity and prolonged lifetime. Magnetism has also been involved in biomedical applications and played significant roles in targeted drug delivery and anti-cancer therapy. We speculate that development of dual cross-linked hydrogels basing biopolymers with multi-functionalities, such as injectable, self-healing, magnetic and anti-bacterial properties, would greatly broaden the application for bone tissue regeneration and drug delivery.


Asunto(s)
Quitosano , Hidrogeles , Hidrogeles/farmacología , Hidrogeles/química , Staphylococcus aureus , Escherichia coli , Quitosano/farmacología , Quitosano/química , Durapatita/farmacología , Durapatita/química , Antibacterianos/farmacología , Fenómenos Magnéticos
19.
Nat Mater ; 21(4): 423-429, 2022 04.
Artículo en Inglés | MEDLINE | ID: mdl-35190656

RESUMEN

Charge neutrality and their expected itinerant nature makes excitons potential transmitters of information. However, exciton mobility remains inaccessible to traditional optical experiments that only create and detect excitons with negligible momentum. Here, using angle-resolved photoemission spectroscopy, we detect dispersing excitons in the quasi-one-dimensional metallic trichalcogenide, TaSe3. The low density of conduction electrons and the low dimensionality in TaSe3 combined with a polaronic renormalization of the conduction band and the poorly screened interaction between these polarons and photo-induced valence holes leads to various excitonic bound states that we interpret as intrachain and interchain excitons, and possibly trions. The thresholds for the formation of a photo-hole together with an exciton appear as side valence bands with dispersions nearly parallel to the main valence band, but shifted to lower excitation energies. The energy separation between side and main valence bands can be controlled by surface doping, enabling the tuning of certain exciton properties.


Asunto(s)
Electrones
20.
Front Microbiol ; 13: 1101975, 2022.
Artículo en Inglés | MEDLINE | ID: mdl-36713202

RESUMEN

Continuous cropping of watermelon (Citrullus lanatus) may lead to soil degradation. As a soil conditioner, microbial agent has great potential in improving soil function and enhancing plant growth. In this study, we aimed to explore how microbial agent relieves the soil sickness of watermelon by analyzing watermelon performance, soil physicochemical properties and microbial community structures. Results suggested that microbial agent treatments significantly changed the photosynthetic efficiency of upper and lower leaves, which helped improve the growth of watermelon. The single fruit weight, fruit sugar degree and total phosphorus of soil following treatment with a mixture of Paecilomyces lilacinus DZ910 and Bacillus subtilis KC1723 (treatment D_K) were higher than those in single biofertilizer treatments and control. The soil microbial community under microbial agent treatments also changed significantly, indicating the feasibility of using microbial agents as soil remediations. The proportions of Pseudomonas and Flavobacterium, changed significantly after using microbial agents. Pseudomonas increased significantly after B. subtilis KC1723 and D_K treatments, while Flavobacterium increased significantly after using all three kinds of microbial agents compared to control. Increases in these bacteria were positively correlated with agronomic variables of watermelon. The fungi Aspergillus and Neocosmospora in the soil, which create an soil sickness of watermelon, decreased after KC1723 and D_K treatments. Meanwhile, Aspergillus and Neocosmospora were positively related to Myceliophthora incidence and negatively correlated with watermelon growth (single fruit weight and photosynthetic efficiency of upper leaves). Our microbial agent, especially D_K, represents a useful technique for alleviating soil sickness in watermelon.

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