Combining ultrahigh sensitivity, spatial resolution, and the capability to resolve chemical information, tip-enhanced Raman spectroscopy (TERS) is a powerful tool to study molecules or nanoscale ...objects. Here we show that TERS can also be a powerful tool in studying two-dimensional materials. We have achieved a 10^{9} Raman signal enhancement and a 0.5 nm spatial resolution using monolayer silicene on Ag(111) as a prototypical 2D material system. Because of the selective enhancement on Raman modes with vertical vibrational components in TERS, our experiment provides direct evidence of the origination of Raman modes in silicene. Furthermore, the ultrahigh sensitivity of TERS allows us to identify different vibrational properties of silicene phases, which differ only in the bucking direction of the Si-Si bonds. Local vibrational features from defects and domain boundaries in silicene can also be identified.
Purpose
To determine the optimal combination of parameters derived from 3T multiparametric (conventional magnetic resonance imaging MRI, diffusion‐weighted DW and dynamic contrast‐enhanced DCE) MRI ...for differentiating malignant from benign orbital lymphoproliferative disorders (OLPDs).
Materials and Methods
Forty patients with OLPDs (18 benign and 22 malignant) underwent conventional 3.0T MR, DW, and DCE‐MRI examination for presurgery evaluation. Conventional MRI features (including tumor laterality, shape, number of involved quadrants, signal intensity on T1‐weighted imaging (WI) and T2WI, flow void sign on T2WI, and findings suggestive of sinusitis) were reviewed, and multivariate logistic regression analysis was used to identify the most significant conventional MRI features. Apparent diffusion coefficient (ADC) and DCE‐MRI derived parameters (area under curve AUC, time to peak TTP, maximum rise slope Slopemax) were measured and compared between two groups. Receiver operating characteristic (ROC) curve analyses were used to determine the diagnostic ability of each combination that was established based on identified qualitative and quantitative parameters.
Results
Multivariate logistic regression analysis showed that the presence of flow void sign on T2WI significantly associated with benign OLPDs (P = 0.034). Malignant OLPDs demonstrated significantly lower ADC (P = 0.001) and AUC (P = 0.002) than benign mimics. ROC analyses indicted that, ADC alone showed the optimal sensitivity (threshold value, 0.886 × 10−3 mm2/s; sensitivity, 90.9%), while a combination of no presence of flow void sign on T2WI + ADC ≤ 0.886 × 10−3 mm2/s + AUC ≤ 7.366 showed optimal specificity (88.9%) in differentiating benign from malignant OLPDs.
Conclusion
Multiparametric MRI can help to differentiate malignant from benign OLPDs. DWI offers optimal sensitivity, while the combination of conventional MRI, DWI, and DCE‐MRI offers optimal specificity.
Level of Evidence: 3
J. Magn. Reson. Imaging 2017;45:167–176.
Elamipretide (EPT), a novel mitochondria-targeted peptide, has been shown to be protective in a range of diseases. However, the effect of EPT in spinal cord injury (SCI) has yet to be elucidated. We ...aimed to investigate whether EPT would inhibit pyroptosis and protect against SCI.
After establishing the SCI model, we determined the biochemical and morphological changes associated with pyroptosis, including neuronal cell death, proinflammatory cytokine expression, and signal pathway levels. Furthermore, mitochondrial function was assessed with flow cytometry, quantitative real-time polymerase chain reaction, and western blot.
Here, we demonstrate that EPT improved locomotor functional recovery following SCI as well as reduced neuronal loss. Moreover, EPT inhibited nucleotide-binding oligomerization domain-like receptor 3 (NLRP3) inflammasome activation and pyroptosis occurrence and decreased pro-inflammatory cytokines levels following SCI. Furthermore, EPT alleviated mitochondrial dysfunction and reduced mitochondrial reactive oxygen species level.
EPT treatment may protect against SCI via inhibition of pyroptosis.
Due to the intrinsic link with (kinetic) nonlinear Fokker–Planck equations and many diverse applications, distribution dependent stochastic differential equations have been investigated intensively ...in recent years. The appearance of the probability distributions (or laws) of the random variables of solutions in the coefficients is a distinct feature of distribution dependent stochastic differential equations. In this paper, under certain averaging conditions, we establish a stochastic averaging principle for distribution dependent stochastic differential equations.
Monolayer molybdenum disulfide (MoS2), a new two-dimensional material beyond graphene, has attracted tremendous attention recently. Its applications in nanoelectronic and thermoelectric devices ...usually require manipulating the thermal transport properties. Using nonequilibrium molecular dynamics simulations, we investigated the effects of lattice defects and mechanical strain on the thermal conductivity of MoS2. We found that the thermal conductivity of monolayer MoS2 can be effectively tuned by introducing even a small amount of lattice defects. For example, a 0.5% concentration of mono-Mo vacancies is able to reduce the thermal conductivity by about 60%. Remarkably, the thermal conductivity of the defected sample can further be tuned by mechanical strain. For example, a 12% tensile strain is able to reduce the thermal conductivity by another 60%. We also found that the tensile strain exerts almost the same impact on the thermal conductivity of both pristine and defective MoS2, which signifies that there is no apparent coupling between defects and strain in affecting the thermal conductivity. Our analyses of the vibrational density of state and spectral energy density show that the underlying mechanisms for these drastic changes are (1) the reduction of the phonon relaxation time arising from phonon–defect scattering and (2) the reduction of the group velocity and heat capacity caused by tensile strain. Our findings here provide important insights and guidelines for the use of monolayer MoS2 in thermal management and thermoelectric devices.
In multiple attribute group decision making (MAGDM) problems, uncertain decision information is well-represented by linguistic term sets (LTSs). These LTSs are easily converted into probabilistic ...linguistic sets (PLTSs). In this paper, a TOPSIS method is proposed for probabilistic linguistic MAGDM in which the attribute weights are completely unknown, and the decision information is in the form of probabilistic linguistic numbers (PLNs). First, the definition of the scoring function is used to solve the probabilistic linguistic entropy, which is then employed to objectively derive the attribute weights. Second, the optimal alternatives are determined by calculating the shortest distance from the probabilistic linguistic positive ideal solution (PLPIS) and on the other side the farthest distance of the probabilistic linguistic negative ideal solution (PLNIS). This proposed method extends the applications range of the traditional entropy-weighted method. Moreover, it doesn’t need the decision-maker to give the attribute weights in advance. Finally, a numerical example for supplier selection of new agricultural machinery products is used to illustrate the use of the proposed method. The result shows the approach is simple, effective and easy to calculate. The proposed method can contribute to the selection of suitable alternative successfully in other selection problems.
Information on biomagnification of alternative brominated flame retardants (ABFRs) is limited and results are inconclusive, due in part to uncertainty in the understanding of predator/prey ...relationships. In the present study, a predatory fish, Channa argus, and several forage fish species were obtained from an ABFR contaminated site. The predator/prey relationships were identified based on fatty acid (FA) signatures in the predator and prey. Biomagnification factors (BMFs) for several ABFRs including decabromodiphenyl ethane (DBDPE), 1,2‑bis(2,4,6‑tribromophenoxy) ethane (BTBPE), hexabromobenzene (HBB), pentabromotoluene (PBT), and pentabromoethylbenzene (PBEB) were estimated based on the identified predator/prey relationships. The results showed that crucian carp was the main prey of C. argus, contributing to 71%–100% to its total diet. The mean BMFs for DBDPE, BTBPE, and HBB were 0.06, 0.40, and 0.91, respectively, indicating trophic dilution of these ABFRs. However, biomagnification of PBT and PBEB, with BMFs of 2.09 and 2.13, respectively, was observed. The BMFs for PBT, PBEB and HBB were comparable to or even higher than those for some polybrominated diphenyl ether (PBDE) congeners estimated in the same individual predator, indicating that these emerging pollutants may pose significant environmental risks. The BMFs for ABFRs and PBDEs were significantly and negatively correlated to the log KOWs of these chemicals, suggesting that the biomagnification of these chemicals was depressed due to their superhydrophobic nature.
•BMFs for ABFRs were estimated based on diet composition of the predator.•PBT and PBEB magnified while DBDPE, BTBPE, and HBB diluted in the predator.•BMFs for ABFRs are comparable to or even higher than those for PBDEs.•One of the few reports on the biomagnification potential of ABFRs.
The highest power conversion efficiencies (PCEs) reported for perovskite solar cells (PSCs) with inverted planar structures are still inferior to those of PSCs with regular structures, mainly because ...of lower open-circuit voltages (
). Here we report a strategy to reduce nonradiative recombination for the inverted devices, based on a simple solution-processed secondary growth technique. This approach produces a wider bandgap top layer and a more n-type perovskite film, which mitigates nonradiative recombination, leading to an increase in
by up to 100 millivolts. We achieved a high
of 1.21 volts without sacrificing photocurrent, corresponding to a voltage deficit of 0.41 volts at a bandgap of 1.62 electron volts. This improvement led to a stabilized power output approaching 21% at the maximum power point.
Epilepsy is a common nervous system disease that is characterized by recurrent seizures. An electroencephalogram (EEG) records neural activity, and it is commonly used for the diagnosis of epilepsy. ...To achieve accurate detection of epileptic seizures, an automatic detection approach of epileptic seizures, integrating complementary ensemble empirical mode decomposition (CEEMD) and extreme gradient boosting (XGBoost), named CEEMD-XGBoost, is proposed. Firstly, the decomposition method, CEEMD, which is capable of effectively reducing the influence of mode mixing and end effects, was utilized to divide raw EEG signals into a set of intrinsic mode functions (
s) and residues. Secondly, the multi-domain features were extracted from raw signals and the decomposed components, and they were further selected according to the importance scores of the extracted features. Finally, XGBoost was applied to develop the epileptic seizure detection model. Experiments were conducted on two benchmark epilepsy EEG datasets, named the Bonn dataset and the CHB-MIT (Children's Hospital Boston and Massachusetts Institute of Technology) dataset, to evaluate the performance of our proposed CEEMD-XGBoost. The extensive experimental results indicated that, compared with some previous EEG classification models, CEEMD-XGBoost can significantly enhance the detection performance of epileptic seizures in terms of sensitivity, specificity, and accuracy.
The atomic structures of self-assembled silicon nanoribbons and magic clusters on Ag(110) substrate have been studied by high-resolution noncontact atomic force microscopy (nc-AFM) and tip-enhanced ...Raman spectroscopy (TERS). Pentagon-ring structures in Si nanoribbons and clusters have been directly visualized. Moreover, the vibrational fingerprints of individual Si nanoribbon and cluster retrieved by subnanometer resolution TERS confirm the pentagonal nature of both Si nanoribbons and clusters. This work demonstrates that Si pentagon can be an important element in building silicon nanostructures, which may find important applications for future nanoelectronic devices based on silicon.
PDF
