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1.
Nat Mater ; 22(1): 84-91, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36175521

RESUMO

Landau band crossings typically stem from the intra-band evolution of electronic states in magnetic fields and enhance the interaction effect in their vicinity. Here in the extreme quantum limit of topological insulator HfTe5, we report the observation of a topological Lifshitz transition from inter-band Landau level crossings using magneto-infrared spectroscopy. By tracking the Landau level transitions, we demonstrate that band inversion drives the zeroth Landau bands to cross with each other after 4.5 T and forms a one-dimensional Weyl mode with the fundamental gap persistently closed. The unusual reduction of the zeroth Landau level transition activity suggests a topological Lifshitz transition at 21 T, which shifts the Weyl mode close to the Fermi level. As a result, a broad and asymmetric absorption feature emerges due to the Pauli blocking effect in one dimension, along with a distinctive negative magneto-resistivity. Our results provide a strategy for realizing one-dimensional Weyl quasiparticles in bulk crystals.

2.
BMC Gastroenterol ; 24(1): 208, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38902604

RESUMO

BACKGROUND: In Chinese healthcare settings, drug selection decisions are predominantly influenced by the Pharmacy & Therapeutics Committee (PTC). This study evaluates two recently introduced potassium-competitive acid blockers, vonoprazan (VPZ) and tegoprazan (TPZ), utilizing the Evidence and Value: Impact on DEcisionMaking (EVIDEM) framework. METHODS: The study employed the 10th edition of EVIDEM, which includes a core model with five domains and 13 criteria. Two independent expert panels were involved: the PTC expert panel, tasked with assigning weights using a 5-point scale, defining scoring indicators, examining the evidence matrix, scoring, and decision-making; and the evidence matrix expert panel, responsible for conducting a systematic literature review, creating the evidence matrix, and evaluating the value contributions of VPZ and TPZ. RESULTS: The analysis estimated the value contributions of VPZ and TPZ to be 0.59 and 0.54, respectively. The domain of 'economic consequences of intervention' showed the most significant variation in value contribution between the two drugs, followed by 'comparative outcomes of intervention' and 'type of benefit of intervention'. CONCLUSION: Employing the EVIDEM framework, VPZ's value contribution was found to be marginally superior to that of TPZ. The EVIDEM framework demonstrates potential for broader application in Chinese medical institutions.


Assuntos
Refluxo Gastroesofágico , Inibidores da Bomba de Prótons , Pirróis , Sulfonamidas , Sulfonamidas/uso terapêutico , Pirróis/uso terapêutico , Humanos , Inibidores da Bomba de Prótons/uso terapêutico , China , Refluxo Gastroesofágico/tratamento farmacológico , Técnicas de Apoio para a Decisão , Análise Custo-Benefício
3.
Langmuir ; 36(37): 11161-11168, 2020 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-32844659

RESUMO

In this work, an irregular calixpyridinium-suramin sodium supramolecular assembly was constructed by the strong host-guest electrostatic interactions. More interestingly, a novel regular spherical supramolecular assembly was also fabricated by the hydrogen bonding interactions between suramin sodium and the UV accelerated addition product of deprotonated calixpyridinium in water. The same principle was also applied to construct a UV accelerated regular spherical self-assembly by the addition product of deprotonated calixpyridinium in water. Compared with the complicated and irreversible covalent connection of the light-responsive groups to the building block, which is one of the common means of obtaining light-responsive supramolecular systems, this finding not only provides a smart, facile, and universally applicable method to construct deprotonated calixpyridinium-based light-responsive host-guest systems but also provides a new idea for the development of other novel light-responsive building blocks.

4.
Glob Chang Biol ; 20(10): 3222-8, 2014 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24615991

RESUMO

Nitrogen (N) deposition significantly affects the soil carbon (C) cycle process of forests. However, the influence of different types of N on it still remained unclear. In this work, ammonium nitrate was selected as an inorganic N (IN) source, while urea and glycine were chosen as organic N (ON) sources. Different ratios of IN to ON (1 : 4, 2 : 3, 3 : 2, 4 : 1, and 5 : 0) were mixed with equal total amounts and then used to fertilize temperate forest soils for 2 years. Results showed that IN deposition inhibited soil C cycle processes, such as soil respiration, soil organic C decomposition, and enzymatic activities, and induced the accumulation of recalcitrant organic C. By contrast, ON deposition promoted these processes. Addition of ON also resulted in accelerated transformation of recalcitrant compounds into labile compounds and increased CO2 efflux. Meanwhile, greater ON deposition may convert C sequestration in forest soils into C source. These results indicated the importance of the IN to ON ratio in controlling the soil C cycle, which can consequently change the ecological effect of N deposition.


Assuntos
Ciclo do Carbono , Carbono/química , Nitrogênio/química , Solo/química , China , Enzimas/isolamento & purificação , Florestas , Glicina/química , Nitratos/química , Ureia/química
5.
Chemosphere ; 353: 141627, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38447899

RESUMO

Antibiotics have garnered growing attention as pharmaceuticals ubiquitously present in human society. Within the soil environment, antibiotics exhibit a propensity for high environmental persistence, thereby posing a potential threat to the ecosystem. However, research on antibiotics in agricultural-pastoral ecotone soils is scarce. This study investigates the occurrence, distribution and risk of 11 common antibiotics in agricultural soils of the agro-pastoral transition zone in Horqin Left Middle Banner, eastern Inner Mongolia. The total concentration varies from not detectable to 609.62 µg/kg. Tetracyclines are the dominant antibiotic, with a higher detection frequency than Macrolides and Sulfonamides. The detection rates of the three types of antibiotics differ significantly. The study also finds that soil properties (organic matter content, pH, bulk density, clay, cation exchange capacity have no significant correlation with antibiotics in soil. Moreover, spatial regression analysis reveals that population density is the primary factor influencing the spatial distribution of antibiotics in soil. Ecological risk assessment shows that clarithromycin and erythromycin are the two most harmful factors in the ecological risk of agricultural soil.


Assuntos
Antibacterianos , Poluentes do Solo , Humanos , Antibacterianos/análise , Solo/química , Ecossistema , Poluentes do Solo/análise , China , Monitoramento Ambiental
6.
PLoS One ; 19(3): e0298683, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38483882

RESUMO

Urbanization leads to dramatic changes in habitat quality, which significantly affects population health. Research on the coupling coordination relationship between new urbanization and health production efficiency is conducive to improving residents' well-being and urban sustainable development. In this article, we adopted the super-efficient SBM model and entropy value method separately to evaluate the spatiotemporal variation characteristics of health production efficiency and new urbanization in China. Then, we used the coupling coordination degree model to investigate the interactive coercing relationship between new urbanization and health production efficiency. Finally, the panel Tobit model is used to analyze the factors influencing the coupled coordination of the two systems. The results showed that the new urbanization levels of 31 provinces in China have all steadily increased from 2003 to 2018. Health production efficiency exhibited a fluctuating but increasing trend, and its regional differences are gradually narrowing. Health production efficiency and new urbanization have developed in a more coordinated direction, with a spatial pattern of "high in the southeast and low in the northwest." Meanwhile, the relative development characteristics between the two systems have constantly changed, from the new urbanization lagged type to the two systems synchronized type and the health production efficiency lagged type. Population density, economic development level, government financial investment, and government health investment positively impact the coupling coordination degree of the two systems. In comparison, individual health investment harms the harmonization of the two systems.


Assuntos
Ecossistema , Urbanização , Desenvolvimento Econômico , Eficiência , China , Cidades
7.
Micromachines (Basel) ; 15(5)2024 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-38793164

RESUMO

Two-dimensional (2D) transition metal dichalcogenides (TMDs) are garnering considerable scientific interest, prompting discussion regarding their prospective applications in the fields of nanoelectronics and spintronics while also fueling groundbreaking discoveries in phenomena such as the fractional quantum anomalous Hall effect (FQAHE) and exciton dynamics. The abundance of binary compound TMDs, such as MX2 (M = Mo, W; X = S, Se, Te), has unlocked myriad avenues of exploration. However, the exploration of ternary compound TMDs remains relatively limited, with notable examples being Ta2NiS5 and Ta2NiSe5. In this study, we report the synthesis of a new 2D ternary compound TMD materials, Ta3VSe8, employing the chemical vapor transport (CVT) method. The as-grown bulk crystal is shiny and can be easily exfoliated. The crystal quality and structure are verified by X-ray diffraction (XRD), while the surface morphology, stoichiometric ratio, and uniformity are determined by scanning electron microscopy (SEM). Although the phonon property is found stable at different temperatures, magneto-resistivity evolves. These findings provide a possible approach for the realization and exploration of ternary compound TMDs.

8.
J Hazard Mater ; 470: 134111, 2024 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-38581870

RESUMO

Microplastics (MPs) pose a significant global concern, requiring a multifaceted approach to their risk assessment procedures, especially concerning their characteristics in the environment. The Horqin Left Middle Banner in Northeast China was chosen for the research region to investigate the abundance, composition, distribution, and ecological impact of MPs in surface agricultural soils. The concentrations of MPs ranged from 300 to 12800 items/kg, with a median concentration of 1550 items/kg (average = 1994 items/kg). The normal-sized MPs (500-5000 µm) had a higher relative abundance than small MPs (<500 µm). MPs were mainly derived from textiles and packaging and were affected by atmospheric transportation. Rayon and PET fibers were the main polymers identified. Furthermore, the potential environmental risks posed by the fundamental characteristics (abundance, chemical composition, and size) of MPs were quantified using multiple risk assessment models. The conditional fragmentation model indicated a propensity for MPs to degrade into smaller particles. Ecological risk assessments using pollution load index, pollution hazard index, and potential ecological risk index models revealed varying levels of risk. This study conducted a comprehensive assessment of the ecological risks of MPs based on their environmental characteristics, emphasizing the importance of considering multiple factors in the risk assessment process. ENVIRONMENT IMPLICATION: This study investigates the occurrence, distribution, and ecological risk of microplastics (MPs) in agricultural soils of the Northeast Plain of China, a major food production area. MPs are persistent organic pollutants that can pose threats to soil health, crop quality, and food security. By analyzing the composition, size, and source of MPs, as well as their fragmentation and stability in soil, this study provides valuable data for assessing the environmental risk of MPs in agricultural regions. The study also suggests strategies for mitigating MPs pollution and protecting soil ecosystems.

9.
Int J Biol Macromol ; 266(Pt 2): 131343, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38574934

RESUMO

Exploring biopolymer-based antibacterial packaging materials is promising to tackle the issues caused by petroleum plastic pollution and microbial contamination. Herein, a novel packaging material with two antibacterial modes, continuous and efficient, is constructed by dispersing positively charged spermidine carbon dots (Spd-CDs) in a carrageenan/polyvinyl alcohol (CP) composite biopolymer. The obtained nanocomposite film (CP/CDs film) not only gradually releases the ultra-small Spd-CDs but also rapidly generates reactive oxygen species to inhibit the reproduction of E. coli and S. aureus. Benefiting from the complementary advantages of carrageenan and polyvinyl alcohol, as well as the addition of Spd-CDs, the CP/CDs films exhibit high transparency, good mechanical performance, water vapor barrier ability, low migration, etc. The CP/CDs film as a packaging material is validated to be effective in preventing microbial contamination of pork samples. Our prepared nanocomposite film with sustainability and efficient antibacterial properties is expected as food active packaging.


Assuntos
Antibacterianos , Carragenina , Escherichia coli , Embalagem de Alimentos , Nanocompostos , Álcool de Polivinil , Espermidina , Staphylococcus aureus , Álcool de Polivinil/química , Antibacterianos/farmacologia , Antibacterianos/química , Nanocompostos/química , Carragenina/química , Carragenina/farmacologia , Embalagem de Alimentos/métodos , Escherichia coli/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Espermidina/química , Espermidina/farmacologia , Carbono/química , Pontos Quânticos/química , Testes de Sensibilidade Microbiana , Espécies Reativas de Oxigênio/metabolismo
10.
Nat Commun ; 15(1): 2313, 2024 Mar 14.
Artigo em Inglês | MEDLINE | ID: mdl-38485978

RESUMO

Arising from the extreme/saddle point in electronic bands, Van Hove singularity (VHS) manifests divergent density of states (DOS) and induces various new states of matter such as unconventional superconductivity. VHS is believed to exist in one and two dimensions, but rarely found in three dimension (3D). Here, we report the discovery of 3D VHS in a topological magnet EuCd2As2 by magneto-infrared spectroscopy. External magnetic fields effectively control the exchange interaction in EuCd2As2, and shift 3D Weyl bands continuously, leading to the modification of Fermi velocity and energy dispersion. Above the critical field, the 3D VHS forms and is evidenced by the abrupt emergence of inter-band transitions, which can be quantitatively described by the minimal model of Weyl semimetals. Three additional optical transitions are further predicted theoretically and verified in magneto-near-infrared spectra. Our results pave the way to exploring VHS in 3D systems and uncovering the coordination between electronic correlation and the topological phase.

11.
Sci Bull (Beijing) ; 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38824120

RESUMO

Owing to the outstanding properties provided by nontrivial band topology, topological phases of matter are considered as a promising platform towards low-dissipation electronics, efficient spin-charge conversion, and topological quantum computation. Achieving ferroelectricity in topological materials enables the non-volatile control of the quantum states, which could greatly facilitate topological electronic research. However, ferroelectricity is generally incompatible with systems featuring metallicity due to the screening effect of free carriers. In this study, we report the observation of memristive switching based on the ferroelectric surface state of a topological semimetal (TaSe4)2I. We find that the surface state of (TaSe4)2I presents out-of-plane ferroelectric polarization due to surface reconstruction. With the combination of ferroelectric surface and charge-density-wave-gapped bulk states, an electric-switchable barrier height can be achieved in (TaSe4)2I-metal contact. By employing a multi-terminal-grounding design, we manage to construct a prototype ferroelectric memristor based on (TaSe4)2I with on/off ratio up to 103, endurance over 103 cycles, and good retention characteristics. The origin of the ferroelectric surface state is further investigated by first-principles calculations, which reveals an interplay between ferroelectricity and band topology. The emergence of ferroelectricity in (TaSe4)2I not only demonstrates it as a rare but essential case of ferroelectric topological materials, but also opens new routes towards the implementation of topological materials in functional electronic devices.

12.
Biol Pharm Bull ; 36(10): 1540-8, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-24088253

RESUMO

Sesamin, one of the most abundant lignans in sesame seeds, has been shown to exhibit various pharmacological effects. The aim of this study was to elucidate whether sesamin promotes cell cycle arrest and induces apoptosis in HepG2 cells and further to explore the underlying molecular mechanisms. Here, we found that sesamin inhibited HepG2 cell growth by inducing G2/M phase arrest and apoptosis. Furthermore, sesamin suppressed the constitutive and interleukin (IL)-6-induced signal transducer and activator of transcription 3 (STAT3) signalling pathway in HepG2 cells, leading to regulate the downstream genes, including p53, p21, cyclin proteins and the Bcl-2 protein family. Our studies showed that STAT3 signalling played a key role in sesamin-induced G2/M phase arrest and apoptosis in HepG2 cells. These findings provided a molecular basis for understanding of the effects of sesamin in hepatocellular carcinoma tumour cell proliferation. Therefore, sesamin may thus be a potential chemotherapy drug for liver cancer.


Assuntos
Apoptose/efeitos dos fármacos , Carcinoma Hepatocelular/metabolismo , Pontos de Checagem do Ciclo Celular/efeitos dos fármacos , Dioxóis/farmacologia , Lignanas/farmacologia , Neoplasias Hepáticas/metabolismo , Fator de Transcrição STAT3/antagonistas & inibidores , Sesamum/química , Antineoplásicos Fitogênicos/farmacologia , Antineoplásicos Fitogênicos/uso terapêutico , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Ciclo Celular/efeitos dos fármacos , Inibidor de Quinase Dependente de Ciclina p21/metabolismo , Ciclinas/genética , Ciclinas/metabolismo , Dioxóis/uso terapêutico , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Células Hep G2 , Humanos , Interleucina-6/metabolismo , Lignanas/uso terapêutico , Neoplasias Hepáticas/tratamento farmacológico , Neoplasias Hepáticas/genética , Fitoterapia , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Sementes , Transdução de Sinais , Proteína Supressora de Tumor p53/metabolismo
13.
PLoS One ; 18(2): e0281821, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36809384

RESUMO

A myriad of maternal and neonatal complications can result from delivery of a large-for-gestational-age (LGA) infant. LGA birth rates have increased in many countries since the late 20th century, partially due to a rise in maternal body mass index, which is associated with LGA risk. The objective of the current study was to develop LGA prediction models for women with overweight and obesity for the purpose of clinical decision support in a clinical setting. Maternal characteristics, serum biomarkers and fetal anatomy scan measurements for 465 pregnant women with overweight and obesity before and at approximately 21 weeks gestation were obtained from the PEARS (Pregnancy Exercise and Nutrition with smart phone application support) study data. Random forest, support vector machine, adaptive boosting and extreme gradient boosting algorithms were applied with synthetic minority over-sampling technique to develop probabilistic prediction models. Two models were developed for use in different settings: a clinical setting for white women (AUC-ROC of 0.75); and a clinical setting for women of all ethnicity and regions (AUC-ROC of 0.57). Maternal age, mid upper arm circumference, white cell count at the first antenatal visit, fetal biometry and gestational age at fetal anatomy scan were found to be important predictors of LGA. Pobal HP deprivation index and fetal biometry centiles, which are population-specific, are also important. Moreover, we explained our models with Local Interpretable Model-agnostic Explanations (LIME) to improve explainability, which was proven effective by case studies. Our explainable models can effectively predict the probability of an LGA birth for women with overweight and obesity, and are anticipated to be useful to support clinical decision-making and for the development of early pregnancy intervention strategies to reduce pregnancy complications related to LGA.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Macrossomia Fetal , Recém-Nascido , Feminino , Gravidez , Humanos , Macrossomia Fetal/etiologia , Sobrepeso/complicações , Peso ao Nascer , Aumento de Peso , Obesidade/complicações , Idade Gestacional , Índice de Massa Corporal
14.
Polymers (Basel) ; 15(23)2023 Nov 21.
Artigo em Inglês | MEDLINE | ID: mdl-38231932

RESUMO

Doping with heteroatoms is the main method used to enhance energy storage with carbon materials, and polyatomic doping is one of the main challenges. Hydrothermal carbonization of cellulose was performed at 240 °C for 1 h. Ammonium sulfate and thiourea dopants were selected as the sources of inorganic nitrogen and organic nitrogen in the preparation of supercapacitor carbon. The effects of boric acid on the properties of the resulting hydrochar after KOH activation were examined. The results showed that the proportion of functional groups and the specific surface area of the activated hydrochar were reduced by the addition of boric acid, and the formation of micropores was inhibited. The hydrochar obtained from the reaction of cellulose and organic nitrogen compounds had a better pore size distribution and electrochemical properties after activation. The largest specific surface area (952.27 m2/g) was obtained when thiourea was used as the sole dopant. In a three-electrode system, the specific capacitance of the activated hydrochar reached 235.8 F/g at a current density of 1 A/g. After 20,000 charging and discharging cycles at a current density of 10 A/g, the capacitance retention rate was 99.96%. Therefore, this study showed that supercapacitor carbon with good electrochemical properties was obtained by the direct reactions of cellulose with organic nitrogen compounds.

15.
J Hazard Mater ; 460: 132341, 2023 10 15.
Artigo em Inglês | MEDLINE | ID: mdl-37659236

RESUMO

Pesticides are widely used in agriculture and can pose risks to soil health and environmental quality. This study assessed the occurrence, distribution, ecological risk, and environmental carrying capacity of 56 currently used pesticides and three metabolites in agricultural soils of Horqin Left Middle Banner, a typical Northeast China agricultural area. 29 pesticides were detected, with atrazine, clothianidin, and propiconazole the most common. Clothianidin and difenoconazole were high-risk to non-target organisms according to risk-toxicity exposure ratio and risk quotient approaches. This study provides a comprehensive and improvement framework for pesticide soil environmental carrying capacity (SECC) assessment and soil quality protection early warning. The SECC model showed no pesticides surpassed the soil carrying capacity threshold under the current application pattern. Five pesticides (clothianidin, difenoconazole, propiconazole, atrazine, and imidacloprid) may reach the threshold within 10 years, requiring pesticide reduction and soil quality monitoring. An early warning system based on SECC values and cumulative amounts of pesticides predicted that clothianidin may exceed the threshold within 0.1 years. These pesticides should be prioritized for management and regulation to prevent soil environmental degradation. The findings can help inform policymakers and stakeholders on pesticide management and sustainable agricultural development in Horqin Left Middle Banner and similar regions.


Assuntos
Atrazina , Praguicidas , Praguicidas/toxicidade , Solo , China , Medição de Risco
16.
Int J Med Inform ; 173: 105040, 2023 05.
Artigo em Inglês | MEDLINE | ID: mdl-36907027

RESUMO

BACKGROUND: Clinical decision support systems (CDSSs) can provide various functions and advantages to healthcare delivery. Quality healthcare during pregnancy and childbirth is of vital importance, and machine learning-based CDSSs have shown positive impact on pregnancy care. OBJECTIVE: This paper aims to investigate what has been done in CDSSs in the context of pregnancy care using machine learning, and what aspects require attention from future researchers. METHODS: We conducted a systematic review of existing literature following a structured process of literature search, paper selection and filtering, and data extraction and synthesis. RESULTS: 17 research papers were identified on the topic of CDSS development for different aspects of pregnancy care using various machine learning algorithms. We discovered an overall lack of explainability in the proposed models. We also observed a lack of experimentation, external validation and discussion around culture, ethnicity and race from the source data, with most studies using data from a single centre or country, and an overall lack of awareness of applicability and generalisability of the CDSSs regarding different populations. Finally, we found a gap between machine learning practices and CDSS implementation, and an overall lack of user testing. CONCLUSION: Machine learning-based CDSSs are still under-explored in the context of pregnancy care. Despite the open problems that remain, the few studies that tested a CDSS for pregnancy care reported positive effects, reinforcing the potential of such systems to improve clinical practice. We encourage future researchers to take into consideration the aspects we identified in order for their work to translate into clinical use.


Assuntos
Sistemas de Apoio a Decisões Clínicas , Humanos , Gravidez , Feminino , Atenção à Saúde , Aprendizado de Máquina , Algoritmos , Pesquisa Empírica
17.
J Biomed Opt ; 28(11): 116501, 2023 11.
Artigo em Inglês | MEDLINE | ID: mdl-37937254

RESUMO

Significance: Understanding the optical transmission property of human hair, especially in the infrared regime, is vital in physical, clinical, and biomedical research. However, the majority of infrared spectroscopy on human hair is performed in the reflection mode, which only probes the absorptance of the surface layer. Aim: The direct transmission spectrum of individual hair without horizontal cut offers a rapid and non-destructive test of the hair cortex but is less investigated experimentally due to the small size and strong absorption of the hair. Approach: In this work, we conduct a transmission infrared micro-spectroscopic study on individual human hair with the help of Fourier-transform infrared microscope experimentally. Its high spatial resolution of infrared micro-spectroscopy further allows the comparison among different regions of hair. The geometry effect of the internal hair structure is also quantified using the finite-element simulation, which supports the experimental results. Results: By utilizing direct measurements of the transmission spectrum using a Fourier-transform infrared microscope, the human hair is found to display prominent band filtering behavior. In a case study of adult-onset Still's disease, the corresponding infrared transmission exhibits systematic variations of spectral weight as the disease evolves. Conclusions: Our work implies that the variation of spectral weight may relate to the disordered microscopic structure variation of the hair cortex during an inflammatory attack. Our work reveals the potential of hair infrared transmission spectrum in tracing the variation of hair cortex retrospectively.


Assuntos
Cabelo , Microscopia , Adulto , Humanos , Espectroscopia de Infravermelho com Transformada de Fourier/métodos , Estudos Retrospectivos , Espectrofotometria Infravermelho , Cabelo/diagnóstico por imagem
18.
Polymers (Basel) ; 15(18)2023 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-37765600

RESUMO

Excellent mechanical properties and self-healing properties are very important for the practical application of hydrogel flexible sensors. In this study, acrylic acid and stearyl methyl acrylate were selected as monomers to synthesize hydrophobic association hydrogels, and multi-physically cross-linked hydrogels were synthesized by adding ferric chloride and polyvinyl alcohol to introduce ion interaction and a hydrogen bond cross-linking network. The hydrogels were characterized by FTIR, XRD and SEM, and the mechanical properties and self-healing properties were tested using a universal testing machine. It was confirmed that the strength of the hydrogel was significantly improved with the addition of ferric chloride and polyvinyl alcohol, and the hydrogel still showed good self-healing properties. Further testing of its application as a conductive sensor has demonstrated sensitive and stable motion sensing capabilities. This provides an important reference for high-performance hydrogel sensors with both high strength and self-healing properties.

19.
Adv Sci (Weinh) ; 10(20): e2300413, 2023 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-37116118

RESUMO

Photodetector based on two-dimensional (2D) materials is an ongoing quest in optoelectronics. 2D photodetectors are generally efficient at low illuminating power but suffer severe recombination processes at high power, which results in the sublinear power-dependent photoresponse and lower optoelectronic efficiency. The desirable superlinear photocurrent is mostly achieved by sophisticated 2D heterostructures or device arrays, while 2D materials rarely show intrinsic superlinear photoresponse. This work reports the giant superlinear power dependence of photocurrent based on multilayer Ta2 NiS5 . While the fabricated photodetector exhibits good sensitivity (3.1 mS W-1 per □) and fast photoresponse (31 µs), the bias-, polarization-, and spatial-resolved measurements point to an intrinsic photoconductive mechanism. By increasing the incident power density from 1.5 to 200 µW µm-2 , the photocurrent power dependence varies from sublinear to superlinear. At higher illuminating conditions, prominent superlinearity is observed with a giant power exponent of γ = 1.5. The unusual photoresponse can be explained by a two-recombination-center model where density of states of the recombination centers (RC) effectively closes all recombination channels. The photodetector is integrated into camera for taking photos with enhanced contrast due to superlinearity. This work provides an effective route to enable higher optoelectronic efficiency at extreme conditions.

20.
Polymers (Basel) ; 14(4)2022 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-35215742

RESUMO

Heavy metal pollution is currently an increasing threat to the ecological environment, and the development of novel absorbents with remarkable adsorption performance and cost-effectiveness are highly desired. In this study, a cassava starch-based Pb(II)-imprinted thermo-responsive hydrogel (CPIT) had been prepared by using cassava starch as the bio-substrate, N-isopropyl acrylamide (NIPAM) as the thermo-responsive monomer, and Pb(II) as the template ions. Later, a variety of modern techniques including FTIR, DSC, SEM, and TGA were employed to comprehensively analyze the characteristic functional groups, thermo-responsibility, morphology, and thermal stability of CPIT. The obtained material exhibited superior performance in adsorption of Pb(II) and its maximum adsorption capacity was high-up to 114.6 mg/g under optimized conditions. Notably, the subsequent desorption (regeneration) process was fairly convenient by simply rinsing with cold deionized water and the highest desorption efficiency could be achieved as 93.8%. More importantly, the adsorption capacity of regenerated CPIT still maintained 88.2% of the value of starting material even after 10 recyclings. In addition, the excellence of CPIT in selective adsorption of Pb(II) should also be highlighted as its superior adsorption ability (97.9 mg/g) over the other seven interfering metal ions.

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