Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 196
Filtrar
1.
Front Med (Lausanne) ; 11: 1252073, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38695017

RESUMEN

Objective: This study aims to investigate the current status of multiple HPV infection and its association with cervical lesions in the western region of Guangzhou. Methods: A retrospective analysis of clinical data from cervical cancer screening patients was conducted. The patients were grouped based on HPV genotypes and cervical pathology results to explore the prevalence of high-risk HPV infection and its relationship with cervical lesions in the western region of Guangzhou. The study also analyzed the relationship between high-risk HPV infection and cervical lesions among different age groups. Results: A total of 13,060 patients were included in the study, with an overall infection rate of 18.46% (2,411/13,060). Among them, the infection rate of HPV genotype 16 was 14.14% (341/2,411), HPV genotype 18 was 5.23% (126/2,411), and other 12 high-risk HPV genotypes accounted for 71.96% (1,735/2,411). When comparing the incidence of HSIL+ (high-grade squamous intraepithelial lesion or worse) among different HPV genotypes, the results showed that the HPV 16 infection group (47.50%) had a higher incidence than the HPV 18 infection group (25.40%) and the other 12 high-risk HPV genotypes group (15.97%; P < 0.05). In the multiple infection groups, the pathogenicity rates were 63.64% (7/11) for the 16+18 HPV infection group, 42.97% (55/128) for the 16+other 12 high-risk HPV genotypes infection group, 26.79% (15/56) for the 18+other 12 high-risk HPV genotypes infection group, and 57.14% (8/14) for the 16+18+other 12 high-risk HPV genotypes infection group. These rates were significantly different compared to the single infection group (P <0.01). Although there was no statistically significant difference in the incidence of cervical cancer between the HPV 16 infection group and the HPV 18 infection group, both groups had a higher incidence compared to the group with other 12 high-risk HPV genotypes infection (P < 0.05). Further analysis suggests that the severity of cervical lesions is not associated with the number of high-risk HPV infections, i.e., the severity of cervical lesions is unrelated to multiple HPV infections but is instead related to the pathogenicity of the HPV genotypes. The infection rate and multiple HPV infection rate of women under 35 years old were higher than those of women aged 35 and above (20% vs. 17.1%; 2% vs. 1.3%; P < 0.05). Moreover, the pathogenicity rate of HSIL+ among high-risk HPV infection increased with age. Conclusions: In the western region of Guangzhou, the overall infection rate of high-risk HPV is 18.46%. The severity of cervical lesions is unrelated to multiple HPV infections. The fundamental reason is the distinct pathogenicity of different HPV genotypes. The HSIL+ pathogenicity rates, from high to low, are in sequence for HPV 16, HPV 18, and the other 12 HPV types.

2.
Comput Biol Med ; 174: 108308, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38581998

RESUMEN

Automated Osteosarcoma Segmentation in Multi-modality MRI (AOSMM) holds clinical significance for effective tumor evaluation and treatment planning. However, the precision of AOSMM is challenged by the diverse characteristics of multi-modality MRI and the inherent heterogeneity and boundary ambiguity of osteosarcoma. While numerous methods have made significant strides in automated osteosarcoma segmentation, they primarily focused on the use of a single MRI modality and overlooked the potential benefits of integrating complementary information from other MRI modalities. Furthermore, they did not adequately model the long-range dependencies of complex tumor features, which may lead to insufficiently discriminative feature representations. To this end, we propose a decoupled semantic and boundary learning network (DECIDE) to achieve precise AOSMM with three functional modules. The Multi-modality Feature Fusion and Recalibration (MFR) module adaptively fuses and recalibrates multi-modality features by exploiting their channel-wise dependencies to compute low-rank attention weights for effectively aggregating useful information from different MRI modalities, which promotes complementary learning between multi-modality MRI and enables a more comprehensive tumor characterization. The Lesion Attention Enhancement (LAE) module employs spatial and channel attention mechanisms to capture global contextual dependencies over local features, significantly enhancing the discriminability and representational capacity of intricate tumor features. The Boundary Context Aggregation (BCA) module further enhances semantic representations by utilizing boundary information for effective context aggregation while also ensuring intra-class consistency in cases of boundary ambiguity. Substantial experiments demonstrate that DECIDE achieves exceptional performance in osteosarcoma segmentation, surpassing state-of-the-art methods in terms of accuracy and stability.


Asunto(s)
Neoplasias Óseas , Imagen por Resonancia Magnética , Osteosarcoma , Osteosarcoma/diagnóstico por imagen , Humanos , Imagen por Resonancia Magnética/métodos , Neoplasias Óseas/diagnóstico por imagen , Semántica , Interpretación de Imagen Asistida por Computador/métodos , Imagen Multimodal/métodos
3.
Sci Rep ; 14(1): 9580, 2024 Apr 26.
Artículo en Inglés | MEDLINE | ID: mdl-38671053

RESUMEN

Kagome superconductors AV3Sb5 (A = K, Rb, and Cs) have attracted enormous interest due to the coexistence of charge density wave (CDW) order, unconventional superconductivity (SC) and anomalous Hall effect (AHE). In this paper, we reported an intensive investigation on Cs(V1-xTax)3Sb5 single crystals with systematic Ta doping. Ta was confirmed to be doped into V-site in the Kagome layer from both single crystal X-ray diffraction structural refinement and scanning transmission electron microscopy observation. The highest Ta doping level was found to be about 16%, which is more than twice as much as 7% in Nb-doped CsV3Sb5. With the increase of Ta doping, CDW order was gradually suppressed and finally vanished when the doping level reached to more than 8%. Meanwhile, superconductivity was enhanced with a maximum critical temperature (Tc) of 5.3 K, which is the highest Tc in the bulk crystal of this Kagome system at ambient pressure so far. The µ0Hc2(T) behavior demonstrates that the system is still a two-band superconductor after Ta doping. Based on the electrical transport measurement, a phase diagram was set up to exhibit the evolution of CDW and SC in the Cs(V1-xTax)3Sb5 system. These findings pave a new way to search for new superconductors with higher Tc in the AV3Sb5 family and establish a new platform for tuning and controlling the multiple orders and superconducting states.

4.
Bioorg Med Chem ; 104: 117698, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38552597

RESUMEN

Serotonin reuptake inhibition combined with the action targeting 5-hydroxytryptamine receptor subtypes can serve as a potential target for the development of antidepressant drugs. Herein a series of new aralkyl piperazines and piperidines were designed and synthesized by the structural modifications of the previously discovered aralkyl piperidine compound 1, targeting SSRI/5-HT1A/5-HT7. The results exhibited that compound 5a showed strong binding to 5-HT1A and 5-HT7 (Ki of 0.46 nM, 2.7 nM, respectively) and a high level of serotonin reuptake inhibition (IC50 of 1.9 nM), all of which were significantly elevated compared to 1. In particular, compound 5a showed weaker inhibitory activity against hERG than 1, and demonstrated good stability in liver microsomes in vitro. The preliminary screening using FST indicated that orally administered 5a, at a high dose, could reduce immobility time in mice markedly, indicating potential antidepressant activity.


Asunto(s)
Inhibidores Selectivos de la Recaptación de Serotonina , Serotonina , Ratones , Animales , Piperazina/farmacología , Serotonina/metabolismo , Inhibidores Selectivos de la Recaptación de Serotonina/farmacología , Antidepresivos/farmacología , Antidepresivos/uso terapéutico , Piperidinas/farmacología , Piperazinas/química , Receptor de Serotonina 5-HT1A
6.
Nanomaterials (Basel) ; 14(3)2024 Feb 03.
Artículo en Inglés | MEDLINE | ID: mdl-38334581

RESUMEN

The spatiotemporal evolution of photogenerated charge carriers on surfaces and at interfaces of photoactive materials is an important issue for understanding fundamental physical processes in optoelectronic devices and advanced materials. Conventional optical probe-based microscopes that provide indirect information about the dynamic behavior of photogenerated carriers are inherently limited by their poor spatial resolution and large penetration depth. Herein, we develop an ultrafast scanning electron microscope (USEM) with a planar emitter. The photoelectrons per pulse in this USEM can be two orders of magnitude higher than that of a tip emitter, allowing the capture of high-resolution spatiotemporal images. We used the contrast change of the USEM to examine the dynamic nature of surface carriers in an InGaAs/InP avalanche photodiode (APD) after femtosecond laser excitation. It was observed that the photogenerated carriers showed notable longitudinal drift, lateral diffusion, and carrier recombination associated with the presence of photovoltaic potential at the surface. This work demonstrates an in situ multiphysics USEM platform with the capability to stroboscopically record carrier dynamics in space and time.

7.
Sci Rep ; 14(1): 4290, 2024 02 21.
Artículo en Inglés | MEDLINE | ID: mdl-38383549

RESUMEN

Emerging technological innovations offer the potential for experiential engagement through virtual scenarios, yet the viability of this approach for educational purposes remains significantly underexplored. This study aims to assess the feasibility of Augmented Reality (AR) and Virtual Reality (VR) technologies in providing users with aesthetic experiences when visiting digital exhibitions. A total of 190 students participated in this investigation. The control group visited traditional exhibits at the Palace Museum in Beijing. This group underwent a survey to evaluate their acquired aesthetic experience. In contrast, the experimental group, comprising 96 students, engaged with VR/AR scenarios at the Palace Museum in Beijing. Accordingly, students in the experimental group were also surveyed to evaluate both their aesthetic experiences and, additionally, their user experiences. The survey results unveiled significant distinctions in aesthetic experiences between students in the control and experimental groups. Moreover, there were notable correlations between individual variables related to user and aesthetic experiences within the experimental group. Furthermore, the study revealed disparities in both user and aesthetic experiences among male and female students. The findings have implications for aesthetic education teachers and officials in the context of developing sound strategies for providing aesthetic experiences to their students. This information is also of interest to employees of museums, exhibitions, and other cultural facilities, who are interested in holding or hold digital exhibitions.


Asunto(s)
Realidad Aumentada , Realidad Virtual , Humanos , Masculino , Femenino , Estudiantes , Escolaridad , Museos
8.
Nanoscale ; 16(6): 3133-3143, 2024 Feb 08.
Artículo en Inglés | MEDLINE | ID: mdl-38258484

RESUMEN

The capability of femtosecond (fs) laser pulses to manipulate topological spin textures on a very short time scale is sparking considerable interest. This article presents the creation of high density zero field topological spin textures by fs laser excitation in ferrimagnetic TbFeCo amorphous films. The topological spin textures are demonstrated to emerge under fs laser pulse excitation through a unique ultrafast nucleation mechanism, rather than thermal effects. Notably, large intrinsic uniaxial anisotropy could substitute the external magnetic field for the creation and stabilization of topological spin textures, which is further verified by the corresponding micromagnetic simulation. The ultrafast switching between topological trivial and nontrivial magnetic states is realized at an optimum magnitude of magnetic field and laser fluence. Our results would broaden the options to generate zero-field topological spin textures from versatile magnetic states and provides a new perspective for ultrafast switching of 0/1 magnetic states in spintronic devices.

9.
Eur J Radiol ; 169: 111155, 2023 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38155592

RESUMEN

PURPOSE: To explore potential feasibility of texture features in magnetic susceptibility and R2* maps for evaluating liver fibrosis. METHODS: Thirty-one patients (median age 46 years; 22 male) with chronic liver disease were prospectively recruited and underwent magnetic resonance imaging (MRI), blood tests, and liver biopsy. Susceptibility and R2* maps were obtained using a 3-dimensional volumetric interpolated breath-hold examination sequence with a 3T MRI scanner. Texture features, including histogram, gray-level co-occurrence matrix (GLCM), gray-level dependence matrix (GLDM), gray-level run length matrix (GLRLM), gray-level size zone matrix (GLSZM), and neighboring gray tone difference matrix (NGTDM) features, were extracted. Texture features and blood test results of non-significant (Ishak-F < 3) and significant fibrosis patients (Ishak-F ≥ 3) were compared, and correlations with Ishak-F stages were analyzed. Areas under the curve (AUCs) were calculated to determine the efficacy for evaluating liver fibrosis. RESULTS: Nine texture features of susceptibility maps and 19 features of R2* maps were significantly different between non-significant and significant fibrosis groups (all P < 0.05). Large dependence high gray-level emphasis (LDHGLE) of GLDM and long run high gray-level emphasis (LRHGLE) of GLRLM in R2* maps showed significantly negative and good correlations with Ishak-F stages (r = -0.616, P < 0.001; r = -0.637, P < 0.001). Busyness (NGTDM) in susceptibility maps, LDHGLE of GLDM and LRHGLE of GLRLM in R2* maps yield the highest AUCs (AUC = 0.786, P = 0.007; AUC = 0.807, P = 0.004; AUC = 0.819, P = 0.003). CONCLUSION: Texture characteristics of susceptibility and R2* maps revealed possible staging values for liver fibrosis. Susceptibility and R2*-based texture analysis may be a useful and noninvasive method for staging liver fibrosis.


Asunto(s)
Cirrosis Hepática , Imagen por Resonancia Magnética , Humanos , Masculino , Persona de Mediana Edad , Cirrosis Hepática/diagnóstico por imagen , Cirrosis Hepática/patología , Imagen por Resonancia Magnética/métodos
10.
Struct Dyn ; 10(6): 064102, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-38026579

RESUMEN

Ultrafast electron diffraction has been proven to be a powerful tool for the study of coherent acoustic phonons owing to its high sensitivity to crystal structures. However, this sensitivity leads to complicated behavior of the diffraction intensity, which complicates the analysis process of phonons, especially higher harmonics. Here, we theoretically analyze the effects of photoinduced coherent transverse and longitudinal acoustic phonons on electron diffraction to provide a guide for the exploitation and modulation of coherent phonons. The simulation of the electron diffraction was performed in 30-nm films with different optical penetration depths based on the atomic displacements obtained by solving the wave equation. The simulation results exhibit a complex relationship between the frequencies of the phonons and diffraction signals, which highly depends on the laser penetration depth, sample thickness, and temporal stress distribution. In addition, an intensity decomposition method is proposed to account for the in-phase oscillation and high harmonics caused by inhomogeneous excitation. These results can provide new perspectives and insights for a comprehensive and accurate understanding of the lattice response under coherent phonons.

11.
Medicine (Baltimore) ; 102(44): e35907, 2023 Nov 03.
Artículo en Inglés | MEDLINE | ID: mdl-37932970

RESUMEN

RATIONALE: Ovarian squamous cell carcinoma (OSCC) is an exceedingly rare subtype, and high-risk human papillomavirus (HPV)-related OSCC is even rarer. PATIENT CONCERNS: An 8-cm diameter ovarian cyst was detected during a routine B-ultrasound examination, and the patient underwent laparoscopic surgery. Postoperative pathological examination revealed HPV-16-related OSCC involving adjacent uterine tissue. The patient received postoperative radiotherapy and chemotherapy. DIAGNOSES: High-risk HPV-related OSCC. INTERVENTIONS: No. OUTCOMES: The patient was finally diagnosed with high-risk HPV-related OSCC and underwent surgical treatment. LESSONS SUBSECTIONS: In patients with high-grade cervical intraepithelial neoplasia who have undergone cervical conization and maintained annual HPV negativity, the possibility of high-risk HPV-related OSCC should be considered, despite its extreme rarity. Vigilance is essential in the presence of ovarian cysts even after HPV clearance.


Asunto(s)
Carcinoma de Células Escamosas , Neoplasias Ováricas , Infecciones por Papillomavirus , Displasia del Cuello del Útero , Neoplasias del Cuello Uterino , Femenino , Humanos , Neoplasias del Cuello Uterino/patología , Carcinoma Epitelial de Ovario , Papillomaviridae
12.
Front Public Health ; 11: 1251440, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37799153

RESUMEN

Purpose: This study aims to address the existing data gap regarding the status of high-risk human papillomavirus (HR-HPV) infection and the distribution of HR-HPV subtypes among women in rural areas of Nyingchi City, Tibet. The research objectives include providing insights for HPV vaccine development. Methods: The research collected data from two rounds of cancer screening conducted among rural women in Nyingchi City, Tibet, from 2019 to 2022. HR-HPV subtype gene detection was performed using the PCR fluorescence method on the collected samples. And then analyzed the HR-HPV infection rate among rural women in Nyingchi City, Tibet, as well as the infection rate of different HR-HPV subtypes and their distribution across different age groups. A comparison was made between the infection rates of women in rural areas outside the Qinghai-Tibet Plateau and those in Nyingchi City. Results: A total of 15,687 cases included. The overall HR-HPV infection rate among women in rural areas of Nyingchi City, Tibet, was 13.00% (2040/15,687), which was significantly higher than the rate among women in rural areas outside the Qinghai-Tibet Plateau (7.82% (9,249/118,237); χ2 = 635.7, p < 0.001). The highest HPV infection rate was observed in the 35-39 age group, with a rate of 15.31% (499/3260), which was significantly higher than the rate of 7.22% (1827/25,322) among women in the same age group in rural areas outside the Qinghai-Tibet Plateau (χ2 = 253.00, p < 0.001). The lowest HPV infection rate was found in the 50-54 age group, with a rate of 9.69% (246/2540), which was statistically different from the rate of 8.14% (1,604/19,698) among women in the same age group outside the Qinghai-Tibet Plateau (χ2 = 17.68, p < 0.001). The top three HR-HPV subtypes among women in rural areas of Nyingchi City, Tibet, were HPV52 (20.15%, 411/2040), HPV16 (12.45%, 254/2040), and HPV58 (11.96%, 244/2040). These findings align with the top three HR-HPV subtypes among women in rural areas outside the Qinghai-Tibet Plateau. Furthermore, the top three HR-HPV subtypes among women aged 35-39, 40-44, and 45-49 in rural areas of Nyingchi City, Tibet, were HPV52, HPV16, and HPV58. In conclusion, the HR-HPV infection rate among women in rural areas of Nyingchi City, Tibet, is significantly higher compared to women in rural areas outside the Qinghai-Tibet Plateau, with consistent patterns observed in the distribution of the top three HR-HPV subtypes between the two regions.


Asunto(s)
Infecciones por Papillomavirus , Humanos , Femenino , Adulto , Persona de Mediana Edad , Tibet/epidemiología , Infecciones por Papillomavirus/epidemiología , Virus del Papiloma Humano , Genotipo , Papillomaviridae/genética , Papillomavirus Humano 16/genética
13.
Nat Commun ; 14(1): 5857, 2023 Sep 20.
Artículo en Inglés | MEDLINE | ID: mdl-37730686

RESUMEN

Strong electron-photon interactions occurring in a dielectric laser accelerator provide the potential for development of a compact electron accelerator. Theoretically, metallic materials exhibiting notable surface plasmon-field enhancements can possibly generate a high electron acceleration capability. Here, we present a design for metallic material-based on-chip laser-driven accelerators that show a remarkable electron acceleration capability, as demonstrated in ultrafast electron microscopy investigations. Under phase-matching conditions, efficient and continuous acceleration of free electrons on a periodic nanostructure can be achieved. Importantly, an asymmetric spectral structure in which the vast majority of the electrons are in the energy-gain states has been obtained by means of a periodic bowtie-structure accelerator. Due to the presence of surface plasmon enhancement and nonlinear optical effects, the maximum acceleration gradient can reach as high as 0.335 GeV/m. This demonstrates that metallic laser accelerator could provide a way to develop compact accelerators on chip.

14.
Phys Rev Lett ; 131(9): 098202, 2023 Sep 01.
Artículo en Inglés | MEDLINE | ID: mdl-37721830

RESUMEN

Packing structures of granular disks are reconstructed using magnetic resonance imaging techniques. As packing fraction increases, the packing structure transforms from a nematic loose packing to a dense packing with randomly oriented stacks. According to our model based on Edwards' volume ensemble, stack structures are statistically favored when the effective temperature decreases, which has a lower structural anisotropy than single disks, and brings down the global orientational order consequently. This mechanism identified in athermal granular materials can help us understand the nonergodic characteristics of disklike particle assemblies such as discotic mesogens and clays.

15.
World J Surg Oncol ; 21(1): 171, 2023 Jun 07.
Artículo en Inglés | MEDLINE | ID: mdl-37280630

RESUMEN

BACKGROUND: Colorectal cancer (CRC) is the second leading cause of cancer-related deaths globally. It is essential to identify new CRC-associated therapeutic targets and diagnostic biomarkers. Previous studies have demonstrated that a series of circular RNAs (circRNAs) play a crucial role in CRC pathogenesis. This study assessed the potential of hsa_circ_0064559 in tumor cell growth and progression of CRC. METHODS: Six pairs of matched CRC and normal colorectal tissue samples were sequenced using the Affymetrix Clariom D array. Using RNA interference, the expression of thirteen circRNAs was knocked down in CRC cells. The proliferation of CRC cell lines (RKO and SW620 cells) was detected using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay. Apoptosis and cell cycle were determined by flow-cytometric analysis. An in vivo study uses nude mice to establish a CRC mouse model. The differentially expressed genes were analyzed using Affymetrix primeview human GeneChip array and verified by polymerase chain reaction. RESULTS: Affymetrix Clariom D array analysis revealed that thirteen circRNAs were upregulated in CRC. The proliferation of CRC cell lines was decreased, while the proportion of apoptotic and G1 phase cells was higher after hsa_circ_0064559 knockdown. In vivo xenograft nude mice model revealed that the volume and weight of the tumor were reduced by hsa_circ_0064559 knockdown. In Affymetrix primeview human GeneChip array, we found six upregulated genes (STAT1, ATF2, TNFRSF10B, TGFBR2, BAX, and SQSTM1) and two downregulated genes (SLC4A7 and CD274) related to apoptosis and proliferation of colorectal cancer cells after hsa_circ_0064559 knockdown. CONCLUSIONS: The hsa_circ_0064559 knockdown could inhibit the proliferation, promote apoptosis in CRC cell lines in vitro, and inhibit the development of CRC tumors in vivo. The mechanism may be related to activating a wide range of signaling pathways. The hsa_circ_0064559 may be a potential biomarker for early diagnosis or prognosis of CRC and a novel drug target for CRC therapy.


Asunto(s)
Neoplasias Colorrectales , MicroARNs , Animales , Ratones , Humanos , ARN Circular/genética , ARN Circular/metabolismo , Ratones Desnudos , Línea Celular Tumoral , Proliferación Celular/genética , Neoplasias Colorrectales/patología , Ciclo Celular , MicroARNs/genética , Regulación Neoplásica de la Expresión Génica
16.
ACS Appl Mater Interfaces ; 15(21): 26215-26224, 2023 May 31.
Artículo en Inglés | MEDLINE | ID: mdl-37212392

RESUMEN

Increasing the thickness of a superconducting layer and simultaneously reducing the thickness effect in iron-based superconducting coated conductors are particularly essential for improving the critical current Ic. Here, for the first time, we have deposited high-performance FeSe0.5Te0.5 (FST) superconducting films up to 2 µm on LaMnO3-buffered metal tapes by pulsed laser deposition. An interface engineering strategy, alternating growth of a 10 nm-thick nonsuperconducting FST seed layer and a 400 nm-thick FST superconducting layer, was employed to guarantee the crystalline quality of the films with thicknesses of the order of micrometers, resulting in a highly biaxial texture with grain boundary misorientation angle less than the critical value θc ∼ 9°. Moreover, the thickness effect, that the critical current density (Jc) shows a clear dependence on thickness as in cuprates, is reduced by the interface engineering. Also, the maximum Jc was found for a 400 nm-thick film with 1.3 MA/cm2 in self-field at 4.2 K and 0.71 MA/cm2 (H∥ab) and 0.50 MA/cm2 (H∥c) at 9 T. Anisotropic Ginzburg-Landau scaling indicates that the major pinning centers vary from correlated to uncorrelated as the film thickness increases, while the thickness effect is most likely related to the weakening of flux pinning by the fluctuation of charge-carrier mean free path (δl) and strengthening of flux pinning caused by the variation of superconducting transition temperature (δTc) due to off-stoichiometry with thickness.

17.
J Phys Condens Matter ; 35(30)2023 Apr 27.
Artículo en Inglés | MEDLINE | ID: mdl-37102208

RESUMEN

Fe-based superconductors are one of the current research focuses. FeTe is unique in the series of FeSe1-xTex, since it is nonsuperconducting near the FeTe side in the phase diagram in contrast to the presence of superconductivity in other region. However, FeTe thin films become superconducting after oxygen annealing and the mechanism remains elusive. Here, we report the temperature dependences of resistivity, Hall effect and magnetoresistance (MR) of a series of FeTe thin films with different amounts of excess Fe and oxygen. These properties show dramatic changes with excess Fe and oxygen incorporation. We found the Hall coefficients are positive for the oxygen-annealed samples, in contrast to the transition from positive to negative below 50 K for the vacuum-annealed samples. For all samples, both the resistivity and Hall coefficient show a dramatic drop, respectively, at around 50 K-75 K, implying coexistence of superconductivity and antiferromagnetic order for the oxygen-annealed samples. The vacuum-annealed samples show both positive and negative values of MR depending on temperature, while negative MR dominates for the oxygen-annealed samples. We also found that oxygen annealing reduces the excess Fe in FeTe, which has been neglected before. The results are discussed in terms of several contributions, and a comparison is made between the oxygen-annealed FeTe thin films and FeSe1-xTex. This work is helpful for shedding light on the understanding of oxygen-annealed FeTe thin films.

18.
Sci Rep ; 13(1): 2212, 2023 02 07.
Artículo en Inglés | MEDLINE | ID: mdl-36750607

RESUMEN

Magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) have made great successes in clinical diagnosis, medical research, and neurological science. MRI provides high resolution anatomical images of tissues/organs, and MRS provides information of the functional molecules related to a specific tissue/organ. However, it is difficult for classic MRI/MRS to selectively image/probe a specific metabolite molecule other than the water or fat in tissues/organs. This greatly limits their applications on the study of the molecular mechanism(s) of metabolism and disease. Herein, we report a series of molecularly targeted MRI/MRS methods to target specific molecules. The optimal control method was used to efficiently prepare the singlet spin orders of varied multi-spin systems and in turn greatly expand the choice of the targeted molecules in the molecularly targeted MRI/MRS. Several molecules, such as N-acetyl-L-aspartic acid (NAA), dopamine (DA), and a tripeptide (alanine-glycine-glycine, AGG), have been used as targeted molecules for molecularly targeted MRI and MRS. We show in vivo NAA-targeted 1H MRS spectrum of a human brain. The high-resolution signal of NAA suggests a promising way to study important issues in molecular biology at the molecular level, e.g., measuring the local pH value of tissue in vivo, demonstrating the high potential of such methods in medicine.


Asunto(s)
Encéfalo , Imagen por Resonancia Magnética , Humanos , Imagen por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética/métodos , Encéfalo/metabolismo , Agua/metabolismo , Ácido Aspártico/metabolismo , Registros
19.
Neuroimage ; 269: 119923, 2023 04 01.
Artículo en Inglés | MEDLINE | ID: mdl-36739101

RESUMEN

BACKGROUND: Microstructural changes in deep gray matter (DGM) nuclei are related to physiological behavior, cognition, and memory. Therefore, it is critical to study age-dependent trajectories of biomarkers in DGM nuclei for understanding brain development and aging, as well as predicting cognitive or neurodegenerative diseases. OBJECTIVES: We aimed to (1) characterize age-dependent trajectories of mean susceptibility, adjusted volume, and total iron content simultaneously in DGM nuclei using quantitative susceptibility mapping (QSM); (2) examine potential contributions of sex related effects to the different age-dependence trajectories of volume and iron deposition; and (3) evaluate the ability of brain age prediction by combining mean magnetic susceptibility and volume of DGM nuclei. METHODS: Magnetic susceptibilities and volumetric values of DGM nuclei were obtained from 220 healthy participants (aged 10-70 years) scanned on a 3T MRI system. Regions of interest (ROIs) were drawn manually on the QSM images. Univariate regression analysis between age and each of the MRI measurements in a single ROI was performed. Pearson correlation coefficients were calculated between magnetic susceptibility and adjusted volume in a single ROI. The statistical significance of sex differences in age-dependent trajectories of magnetic susceptibilities and adjusted volumes were determined using one-way ANCOVA. Multiple regression analysis was used to evaluate the ability to estimate brain age using a combination of the mean susceptibilities and adjusted volumes in multiple DGM nuclei. RESULTS: Mean susceptibility and total iron content increased linearly, quadratically, or exponentially with age in all six DGM nuclei. Negative linear correlation was observed between adjusted volume and age in the head of the caudate nucleus (CN; R2 = 0.196, p < 0.001). Quadratic relationships were found between adjusted volume and age in the putamen (PUT; R2 = 0.335, p < 0.001), globus pallidus (GP; R2 = 0.062, p = 0.001), and dentate nucleus (DN; R2 = 0.077, p < 0.001). Males had higher mean magnetic susceptibility than females in the PUT (p = 0.001), red nucleus (RN; p = 0.002), and substantia nigra (SN; p < 0.001). Adjusted volumes of the CN (p < 0.001), PUT (p = 0.030), GP (p = 0.007), SN (p = 0.021), and DN (p < 0.001) were higher in females than those in males throughout the entire age range (10-70 years old). The total iron content of females was higher than that of males in the CN (p < 0.001), but lower than that of males in the PUT (p = 0.014) and RN (p = 0.043) throughout the entire age range (10-70 years old). Multiple regression analyses revealed that the combination of the mean susceptibility value of the PUT, and the volumes of the CN and PUT had the strongest associations with brain age (R2 = 0.586). CONCLUSIONS: QSM can be used to simultaneously investigate age- and sex- dependent changes in magnetic susceptibility and volume of DGM nuclei, thus enabling a comprehensive understanding of the developmental trajectories of iron accumulation and volume in DGM nuclei during brain development and aging.


Asunto(s)
Encéfalo , Sustancia Gris , Humanos , Masculino , Femenino , Niño , Adolescente , Adulto Joven , Adulto , Persona de Mediana Edad , Anciano , Imagen por Resonancia Magnética/métodos , Envejecimiento , Mapeo Encefálico/métodos , Hierro
20.
J Magn Reson Imaging ; 58(2): 581-590, 2023 08.
Artículo en Inglés | MEDLINE | ID: mdl-36594513

RESUMEN

BACKGROUND: Deep brain stimulation (DBS) of the subthalamic nucleus (STN) improves motor deficits in advanced Parkinson's disease (PD) patients, but the degree of motor improvement varies across individuals. PD pathology involves the changes of iron spatial distribution in the deep gray matter nuclei. PURPOSE: To explore the relationship between the iron spatial distribution and motor improvement among PD patients who underwent STN-DBS surgery in three regions: substantia nigra (SN), STN, and dentate nucleus (DN). STUDY TYPE: Prospective. SUBJECTS: Forty PD patients (49.7 ± 8.8 years, 22 males/18 females) who underwent bilateral STN-DBS. FIELD STRENGTH/SEQUENCE: A 3 T preoperative three-dimensional spoiled bipolar-readout multi-echo gradient recalled echo and two-dimensional fast spin echo sequences. ASSESSMENT: Movement Disorder Society-sponsored revision of the Unified Parkinson's Disease Rating Scale part III (MDS-UPDRS III) scores were assessed 2-3 days before and 6 months after STN-DBS. The first- and second-order texture features in regions of interest were measured on susceptibility maps. STATISTICAL TESTS: Intraclass correlation coefficient was used to determine the consistency of the region of interest volumes delineated by the two raters. Pearson or Spearman's correlation coefficients were used to assess the relationship between motor improvement after DBS and texture features. A P-value <0.05 was considered statistically significant. RESULTS: MDS-UPDRS III scores were reduced by 59.9% after STN-DBS in 40 PD patients. Motor improvement correlated with second-order texture parameters in the SN including angular second moment (r = -0.449), correlation (rho = 0.326), sum of squares (r = 0.402), sum of entropy (rho = 0.421), and entropy (r = 0.410). Additionally, DBS outcome negatively correlated with mean susceptibility values in the DN (r = -0.400). DATA CONCLUSION: PD patients with a more homogeneous iron distribution throughout the SN or a higher iron concentration in the DN responded worse to STN-DBS. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.


Asunto(s)
Estimulación Encefálica Profunda , Enfermedad de Parkinson , Masculino , Femenino , Humanos , Enfermedad de Parkinson/diagnóstico por imagen , Enfermedad de Parkinson/terapia , Resultado del Tratamiento , Estudios Prospectivos , Sustancia Gris/diagnóstico por imagen
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA
...