199 research outputs found
Quantitative three dimensional atomic resolution characterisation of non-stoichiometric nanostructures in doped bismuth ferrite
Over the last decade, the lead-free, environmentally-friendly multiferroic material, BiFeO3 (BFO), has once again received tremendous attention from researchers, not only for its fundamental properties, but also for its potential applications such as novel devices that can be written by an electric field and read by a magnetic field. However, one of the most important limitations for applications is the high leakage current in pure materials. Doping has proved to be an effective way to reduce the leakage current caused by the electron hopping between Fe2+ and Fe3+. In this work, a series of Nd3+ and Ti4+ co-doped BFO compositions have been studied using a combination of atomic resolution imaging and electron energy loss spectroscopy in STEM, especially concentrating on nanostructures within the Bi0.85Nd0.15Fe0.9Ti0.1O3 composition, as nanostructures can play an important role in the properties of a crystal. Two types of novel defects – Nd-rich nanorod precipitates and Ti-cored anti-phase boundaries (APBs) are revealed for the first time. The 3D structures of these defects were fully reconstructed and verified by multislice frozen phonon image simulations. The very formation of these defects was shown to be caused by the excess doping of Ti into the material and their impact upon the matrix is discussed. The nanorods consist of 8 atom columns with two Nd columns in the very center forming the Nd oxide. Density functional theory calculation reveals that the structures of the nanorod and its surrounding perovskites are rather unusual. The Nd in the core is seven coordinated by oxygen while the coordination of B site Fe3+ at its surroundings are just five-coordinated by oxygen due to the strain between the nanorod and the surrounding perovskite. The APB is nonstoichiometric and can be treated as being constructed from two main structural units - terraces and steps. Within the terraces, Ti4+ occupy the centre of the terrace with Ti/Fe alternately occupying either side of the terrace. As for the step, this is constructed from iron oxide alone with a structure similar to -Fe2O3, and Ti is completely absent. Quantitative analysis of the structure shows the APB is negatively charged and this results in electric fields around the APBs that induce a local phase transformation from an antiferroelectric phase to a locally polarised phase in the perovskite matrix. Based on this thorough investigation of these defects, a new ionic compensation mechanism was proposed for reducing the conductivity of BiFeO3 without the complications of introducing non-stoichiometric nanoscale defects
The atomic structure and chemistry of Fe-rich steps on antiphase boundaries in Ti-doped Bi<sub>0.9</sub>Nd<sub>0.15</sub>FeO3
Stepped antiphase boundaries are frequently observed in Ti-doped Bi<sub>0.85</sub>Nd<sub>0.15</sub>FeO<sub>3</sub>, related to the novel planar antiphase boundaries reported recently. The atomic structure and chemistry of these steps are determined by a combination of high angle annular dark field and bright field scanning transmission electron microscopy imaging, together with electron energy loss spectroscopy. The core of these steps is found to consist of 4 edge-sharing FeO<sub>6</sub> octahedra. The structure is confirmed by image simulations using a frozen phonon multislice approach. The steps are also found to be negatively charged and, like the planar boundaries studied previously, result in polarisation of the surrounding perovskite matrix
Adaptive responses of cardiorespiratory system and hormonal parameters to individualized high-intensity interval training using anaerobic power reserve in well-trained rowers
The current study investigated the efficacy of individualizing exercise intensity according to anaerobic power reserve (APR) on hormonal, physiological, and performance adaptations in athletes with different profiles. Sixteen highly-trained male rowers (age = 22 ± 3 years, height = 183 ± 6 cm, weight = 83 ± 7 kg, body fat = 11 ± 2%, experience = 12 ± 5 years) were randomized to a high-intensity interval training consisting of 2 × (6, 6, 8, 8, 10, 10 repetitions from 1st to 6th week, respectively) × 60 s intervals using a rowing ergometer at ∆%30 APR (APR∆%30) or the same sets and repetitions at 130% maximal aerobic power (MAP130%). In both groups, relief intervals were set at 1:1 with 3 min of rest between sets. On four occasions separated by 24 h recovery, participants attended the laboratory to assess 2000-m rowing ergometer performance, maximal oxygen uptake (V̇O2max) and related physiological adaptations, and hormonal parameters. Significant increases were observed in 2000-m performance, V̇O2max, ventilation at V̇O2max, first and second ventilatory threshold, MAP and maximal sprinting power (MSP), total testosterone, and testosterone to cortisol ratio in response to 6 weeks of APR∆%30 and MAP130% protocols. The coefficient of variation (inter-subject variability) in the adaptive response of cardiorespiratory parameters to HIIT performed using the APR∆%30 protocol was lower than those of the MAP130% group. However, this is not the case for hormonal changes. Prescribing HIIT based on an athlete’s APR may help to create a more consistent level of the mechanical and physiological stimulus relative to the athlete’s capacity, potentially leading to more similar adaptations across athletes with varying profiles. Mechanisms influencing total testosterone are multifactorial and are not affected by this approach
Box2Poly: Memory-Efficient Polygon Prediction of Arbitrarily Shaped and Rotated Text
Recently, Transformer-based text detection techniques have sought to predict
polygons by encoding the coordinates of individual boundary vertices using
distinct query features. However, this approach incurs a significant memory
overhead and struggles to effectively capture the intricate relationships
between vertices belonging to the same instance. Consequently, irregular text
layouts often lead to the prediction of outlined vertices, diminishing the
quality of results. To address these challenges, we present an innovative
approach rooted in Sparse R-CNN: a cascade decoding pipeline for polygon
prediction. Our method ensures precision by iteratively refining polygon
predictions, considering both the scale and location of preceding results.
Leveraging this stabilized regression pipeline, even employing just a single
feature vector to guide polygon instance regression yields promising detection
results. Simultaneously, the leverage of instance-level feature proposal
substantially enhances memory efficiency (>50% less vs. the state-of-the-art
method DPText-DETR) and reduces inference speed (>40% less vs. DPText-DETR)
with minor performance drop on benchmarks
A Experiência da Construção do Sujeito Ético-polÃtico nos Espaços do Fórum Bem Maior
RESUMO
Esta dissertação discute a construção do sujeito ético-polÃtico nos espaços de um fórum de desenvolvimento comunitário, chamado Bem Maior, localizado na cidade de Vitória - ES. A partir da narrativa de algumas experiências vivenciadas junto ao Fórum Bem Maior e com base nas entrevistas que realizamos com 16 lideranças atuantes nesse espaço, buscamos acompanhar o processo de constituição ético-polÃtica da subjetividade engendrada quando do encontro com a alteridade.
Recorremos, principalmente, ao pensamento de Michel Foucault, utilizando alguns de seus principais conceitos como ferramentas teóricas de modo a problematizar a relação entre polÃtica e ética. Isso possibilitou-nos pensar a experiência polÃtica situada exatamente na trama articulada entre o poder e a resistência, tomada nos termos éticos do cuidado de si.
Esse estudo pretendeu ressaltar o componente ético de constituição da subjetividade como indispensável para a construção do sujeito polÃtico como cidadão e a possibilidade de limitação de relações de dominação e sujeição por meio de um exercÃcio ético do cuidado e cultivo da liberdade.
Palavras-chave: Cidadania; Ética; PolÃtica
Incorporating ultrasound-based lymph node staging significantly improves the performance of a clinical nomogram for predicting preoperative axillary lymph node metastasis in breast cancer
Models for predicting axillary lymph node metastasis (ALNM) in breast cancer patients are lacking. We aimed to develop an efficient model to accurately predict ALNM. Three hundred fifty-five breast cancer patients were recruited and randomly divided into the training and validation sets. Univariate and multivariate logistic regressions were applied to identify predictors of ALNM. We developed nomograms based on these variables to predict ALNM. The performance of the nomograms was tested using the receiver operating characteristic curve and calibration curve, and a decision curve analysis was performed to assess the clinical utility of the prediction models. The nomograms that included clinical N stage (cN), pathological grade (pathGrade), and hemoglobin accurately predicted ALNM in the training and validation sets (area under the curve [AUC] 0.80 and 0.80, respectively). We then explored the importance of the cN and pathGradesignatures used in the integrated model and developed new nomograms by removing the two variables. The results suggested that the combine-pathGrade nomogram also accurately predicted ALNM in the training and validation sets (AUC 0.78 and 0.78, respectively), but the combine-cN nomogram did not (AUC 0.64 and 0.60, in training and validation sets, respectively). We described a cN-based ALNM prediction model in breast cancer patients, presenting a novel efficient clinical decision nomogram for predicting ALNM
Non-syndromic enlarged vestibular aqueduct caused by novel compound mutations of the SLC26A4 gene: a case report and literature review
Enlarged vestibular aqueduct is an autosomal genetic disease mainly caused by mutations in the SLC26A4 gene and includes non-syndromic and syndromic types. This study aimed to identify genetic defects in a Chinese patient with non-syndromic enlarged vestibular aqueduct (NSEVA) and to investigate the impact of variants on the severity of non-syndromic enlarged vestibular aqueduct. A male patient with NSEVA, aged approximately 6Â years, was recruited for this study. The clinical characteristics and results of auxiliary examinations, including laboratory and imaging examinations, were collected, and 127 common hereditary deafness genes were detected by chip capture high-throughput sequencing. Protein structure predictions, the potential impact of mutations, and multiple sequence alignments were analyzed in silico. Compound heterozygote mutations c.1523_1528delinsAC (p.Thr508Asnfs*3) and c.422T>C (p.Phe141Ser) in the SLC26A4 gene were identified. The novel frameshift mutation c.1523_1528delinsAC produces a severely truncated pendrin protein, and c.422T>C has been suggested to be a disease-causing mutation. Therefore, this study demonstrates that the novel mutation c.1523_1528delinsAC in compound heterozygosity with c.422T>C in the SLC26A4 gene is likely to be the cause of NSEVA. Cochlear implants are the preferred treatment modality for patients with NSEVA and severe-to-profound sensorineural hearing loss Genetic counseling and prenatal diagnosis are essential for early diagnosis. These findings expand the mutational spectrum of SLC26A4 and improve our understanding of the molecular mechanisms underlying NSEVA
Hydrogen Sulfide Protects against Chemical Hypoxia-Induced Injury by Inhibiting ROS-Activated ERK1/2 and p38MAPK Signaling Pathways in PC12 Cells
Hydrogen sulfide (H2S) has been proposed as a novel neuromodulator and neuroprotective agent. Cobalt chloride (CoCl2) is a well-known hypoxia mimetic agent. We have demonstrated that H2S protects against CoCl2-induced injuries in PC12 cells. However, whether the members of mitogen-activated protein kinases (MAPK), in particular, extracellular signal-regulated kinase1/2(ERK1/2) and p38MAPK are involved in the neuroprotection of H2S against chemical hypoxia-induced injuries of PC12 cells is not understood. We observed that CoCl2 induced expression of transcriptional factor hypoxia-inducible factor-1 alpha (HIF-1α), decreased cystathionine-β synthase (CBS, a synthase of H2S) expression, and increased generation of reactive oxygen species (ROS), leading to injuries of the cells, evidenced by decrease in cell viability, dissipation of mitochondrial membrane potential (MMP) , caspase-3 activation and apoptosis, which were attenuated by pretreatment with NaHS (a donor of H2S) or N-acetyl-L cystein (NAC), a ROS scavenger. CoCl2 rapidly activated ERK1/2, p38MAPK and C-Jun N-terminal kinase (JNK). Inhibition of ERK1/2 or p38MAPK or JNK with kinase inhibitors (U0126 or SB203580 or SP600125, respectively) or genetic silencing of ERK1/2 or p38MAPK by RNAi (Si-ERK1/2 or Si-p38MAPK) significantly prevented CoCl2-induced injuries. Pretreatment with NaHS or NAC inhibited not only CoCl2-induced ROS production, but also phosphorylation of ERK1/2 and p38MAPK. Thus, we demonstrated that a concurrent activation of ERK1/2, p38MAPK and JNK participates in CoCl2-induced injuries and that H2S protects PC12 cells against chemical hypoxia-induced injuries by inhibition of ROS-activated ERK1/2 and p38MAPK pathways. Our results suggest that inhibitors of ERK1/2, p38MAPK and JNK or antioxidants may be useful for preventing and treating hypoxia-induced neuronal injury
The First Case of Ischemia-Free Kidney Transplantation in Humans
Background: Ischemia-reperfusion injury (IRI) has been considered an inevitable event in organ transplantation since the first successful kidney transplant was performed in 1954. To avoid IRI, we have established a novel procedure called ischemia-free organ transplantation. Here, we describe the first case of ischemia-free kidney transplantation (IFKT). Materials and Methods: The kidney graft was donated by a 19-year-old brain-dead donor. The recipient was a 47-year-old man with end-stage diabetic nephropathy. The graft was procured, preserved, and implanted without cessation of blood supply using normothermic machine perfusion. Results: The graft appearance, perfusion flow, and urine production suggested that the kidney was functioning well-during the whole procedure. The creatinine dropped rapidly to normal range within 3 days post-transplantation. The levels of serum renal injury markers were low post-transplantation. No rejection or vascular or infectious complications occurred. The patient had an uneventful recovery. Conclusion: This paper marks the first case of IFKT in humans. This innovation may offer a unique solution to optimizing transplant outcomes in kidney transplantation
- …