344 research outputs found
Tuning the potential drop at graphene/protic ionic liquid interface by molecular structure engineering
Ionic liquids (ILs) have been extensively employed in many applications involving interfaces with carbon-based electrodes, such as energy storage devices (batteries or supercapacitors) or electrocatalytic devices, where the way each ion of the IL interacts with the electrode has a strong impact on the overall performance of the device. For instance, the amount of potential difference between the electrode and the bulk of the IL is highly sensitive to the IL composition and it is directly related to the device capacitance. The selection of the most suited pair of ions often proceeds by time-consuming and costly trial-and-error approaches. It is necessary to understand the atomistic features of the interface to determine the effect of each ion on the potential drop. By classical molecular dynamics simulations, we show that it is possible to quickly infer the interface potential arising at the carbon electrode by carefully inspecting the molecular structure of the IL. The ion orientation at the interface is, in fact, determined by the distribution of charges within the molecules. Depending on where charges are located, ions can either lie flat or perpendicular to the interface to minimize the surface energy. The interface potential is found to be mainly determined by ion-ion interactions dictating the interface energy minimization process, whereas ion-electrode interactions are found to enforce higher ordering and charge layers stacking but not to induce selective adsorption of an ion over the other
Active Surface Structure of SnO2 Catalysts for CO2 Reduction Revealed by Ab Initio Simulations
Tin oxide (SnO2) is an efficient catalyst for the CO2 reduction reaction (CO2RR) to formic acid; however, the understanding of the SnO2 surface structure under working electrocatalytic conditions and the nature of catalytically active sites is a current matter of debate. Here, we employ ab initio density functional theory calculations to investigate how the selectivity and reactivity of SnO2 surfaces toward the CO2RR change at varying surface stoichiometry (i.e., reduction degree). Our results show that SnO2(110) surfaces are not catalytically active for the CO2RR or hydrogen evolution reaction, but rather they reduce under an applied external bias, originating surface structures exposing few metal tin layers, which are responsible for formic acid selectivity
Experimental and numerical study of vacuum resin infusion of stiffened carbon fiber reinforced panels
Liquid resin infusion processes are becoming attractive for aeronautic applications as an alternative to conventional autoclave-based processes. They still present several challenges, which can be faced only with an accurate simulation able to optimize the process parameters and to replace traditional time-consuming trial-and-error procedures. This paper presents an experimentally validated model to simulate the resin infusion process of an aeronautical component by accounting for the anisotropic permeability of the reinforcement and the chemophysical and rheological changes in the crosslinking resin. The input parameters of the model have been experimentally determined. The experimental work has been devoted to the study of the curing kinetics and chemorheological behavior of the thermosetting epoxy matrix and to the determination of both the in-plane and out-of-plane permeability of two carbon fiber preforms using an ultrasonic-based method, recently developed by the authors. The numerical simulation of the resin infusion process involved the modeling of the resin flow through the reinforcement, the heat exchange in the part and within the mold, and the crosslinking reaction of the resin. The time necessary to fill the component has been measured by an optical fiber-based equipment and compared with the simulation results
Predictive accuracy of hormone receptors in conservatively treated endometrial hyperplasia and early endometrioid carcinoma
Intrahepatic persistent fetal right umbilical vein: a retrospective study
Introduction: To appraise the incidence and value of intrahepatic persistent right umbilical vein (PRUV). Methods: This was a single-center study. Records of all women with a prenatal diagnosis of intrahepatic PRUV were reviewed. The inclusion criteria were women with gestational age greater than 13 weeks of gestation. Exclusion criteria were fetuses with situs abnormalities, due to the hepatic venous ambiguity, and extrahepatic PRUV. The primary outcome was the incidence of intrahepatic PRUV in our cohort. The secondary outcomes were associated malformations. Results: 219/57,079 cases (0.38%) of intrahepatic PRUV were recorded. The mean gestational age at diagnosis was 21.8 ± 2.9 weeks of gestations. PRUV was isolated in the 76.7%, while in 23.3% was associated with other major or minor abnormalities. The most common associated abnormalities were cardiovascular abnormalities (8.7%), followed by genitourinary abnormalities (6.4%), skeletal abnormalities (4.6%), and central nervous system abnormalities (4.1%). Within the cardiovascular abnormalities, the most common one was ventricular septal defect (six cases). Conclusion: In most cases PRUV is an isolated finding. Associated minor or major malformations are presented in the 23.3% of the cases, so this finding should prompt detailed prenatal assessment of the fetus, with particular regard to cardiovascular system
Histomorphometric analysis of osteocyte lacunae in human and pig: exploring its potential for species discrimination
In recent years, several studies have focused on species discrimination of bone fragments by histological analysis. According to literature, the most consistent distinguishing features are Haversian canal and Haversian system areas. Nonetheless, there is a consistent overlap between human and non-human secondary osteon dimensions. One of the features that have never been analyzed for the purpose of species discrimination is the osteocyte lacuna, a small oblong cavity in which the osteocyte is locked in. The aim of this study is to verify whether there are significant quantitative differences between human and pig lacunae within secondary osteons with similar areas. Study sample comprises the midshaft of long bones (humerus, radius, ulna, femur, tibia, and fibula) of a medieval human adult and a juvenile pig. Sixty-eight secondary osteons with similar areas have been selected for each species and a total of 1224 osteocyte lacunae have been measured. For each osteon, the total number of lacunae was counted, and the following measurements were taken: minimum and maximum diameter, area, perimeter, and circularity of nine lacunae divided between inner, intermediate, and outer lacunae. Statistical analysis showed minimal differences between human and pig in the number of lacunae per osteons and in the minimum diameter (P > 0.05). On the contrary, a significant difference (P < 0.001) has been observed in the maximum diameter, perimeter, area, and circularity. Although there is the need for further research on different species and larger sample, these results highlighted the potential for the use of osteocyte lacunae as an additional parameter for species discrimination. Concerning the difference between the dimensions of osteocyte lacunae based on their position within the osteon (inner, intermediate, and outer lacunae), results showed that their size decreases from the cement line towards the Haversian canal both in human and pig
TCGA molecular groups of endometrial cancer: Pooled data about prognosis
Background: After The Cancer Genome Atlas (TCGA) findings, four novel prognostic groups may direct the management of endometrial cancer (EC): POLE-mutated/ultramutated (POLEmt), microsatellite-instable/hypermutated (MSI), copy-number-low/p53-wild-type (p53wt), and copy-number-high/p53-mutated (p53mt). However, data about prognosis in each group are different across the studies, and definitive pooled estimates are lacking after validation series. Such data may be crucial in directing clinical study design and establishing the optimal tailored management of patients. Aim: To provide pooled estimates of hazard ratio (HR) for overall survival (OS), disease-specific survival (DSS), progression-free survival (PFS) in each prognostic group. Materials and methods: A systematic review and meta-analysis was performed by searching 7 electronic databases, from their inception to April 2019, for studies assessing prognosis in each TCGA EC group. Both univariable and multivariable HR analysis was performed for OS, DSS and PFS in each group, using p53wt as reference group. Results: Six studies with 2818 patients were included. Regarding OS, pooled HRs were 3.179 and 1.986 for p53mt group, 1.522 and 1.192 for MSI group, and 0.589 and 0.795 for POLEmt group at univariable and multivariable analyses, respectively. Regarding DSS, pooled HR were 5.052 and 2.133 for p53mt group, 1.965 and 1.068 for MSI group, and 0.552 and 0.325 for POLEmt group at univariable and multivariable analyses, respectively. Regarding PFS, pooled HR were 3.512 and 1.833 for p53mt group, 1.354 and 0.817 for MSI group, and 0.287 and 0.217 for POLEmt group at univariable and multivariable analyses, respectively. Conclusions: Prognosis of p53mt group is consistently the worst one and is further worsened by unfavorable clinicopathological factors. Prognosis of MSI group overlaps with p53wt group but is worsened by unfavorable clinicopathological factors. Prognosis of POLEmt group is the best one and does not seem to be significantly affected by clinicopathological factors
PTEN as a predictive marker of response to conservative treatment in endometrial hyperplasia and early endometrial cancer. A systematic review and meta-analysis
OBJECTIVE:
Several markers have been studied to predict the responsiveness of endometrial hyperplasia (EH) and early endometrial cancer (EEC) to progestin therapy. PTEN has played a major role in this field, although its predictive significance is still undefined. We aimed to assess if loss of PTEN expression on pre-treatment endometrial specimen may be a predictive markers of response to progestins in EH and EEC.
STUDY DESIGN:
MEDLINE, EMBASE, Web of Sciences, Scopus, ClinicalTrial.gov, OVID and Cochrane Library were searched for relevant articles from the inception to May 2018. All studies assessing PTEN expression as predictive marker in EH and EEC treated with progestin were included. Relative risk (RR) for therapy failure was calculated with 95% confidence interval (CI) and a significant p-value<0.05, with a subgroup analysis based on the histologic category (EEC or EH) and the administration route of progestin (oral or intrauterine).
RESULTS:
Seven cohort studies assessing 376 patients were included. PTEN loss was not significantly associated with the outcome of therapy in the overall analysis (RR = 1.24, 95% CI, 0.88-1.76, p = 0.21), in + the subgroups of EEC (RR = 0.89, 0.32-2.49, p = 0.83), EH (RR = 1.30, 0.90-1.87 p = 0.16), oral progestin (RR = 1.25 0.88-1.79, p = 0.22) and intrauterine device (RR = 1.02, 0.36-2.87, p = 0.97).
CONCLUSION:
PTEN seems not to be useful as predictive marker of response to the conservative treatment of EH and EC, regardless of the administration route (oral or intrauterine) of progestins. We advise future researcher not to further assess PTEN as a stand-alone predictive marker
Common and distinct lateralised patterns of neural coupling during focused attention, open monitoring and loving kindness meditation
Meditation has been integrated into different therapeutic interventions. To inform the evidence-based selection of specific meditation types it is crucial to understand the neural processes associated with different meditation practices. Here we explore commonalities and differences in electroencephalographic oscillatory spatial synchronisation patterns across three important meditation types. Highly experienced meditators engaged in focused attention, open monitoring, and loving kindness meditation. Improving on previous research, our approach avoids comparisons between groups that limited previous findings, while ensuring that the meditation states are reliably established. Employing a novel measure of neural coupling – the imaginary part of EEG coherence – the study revealed that all meditation conditions displayed a common connectivity pattern that is characterised by increased connectivity of (a) broadly distributed delta networks, (b) left-hemispheric theta networks with a local integrating posterior focus, and (c) right-hemispheric alpha networks, with a local integrating parieto-occipital focus. Furthermore, each meditation state also expressed specific synchronisation patterns differentially recruiting left- or right-lateralised beta networks. These observations provide evidence that in addition to global patterns, frequency-specific inter-hemispheric asymmetry is one major feature of meditation, and that mental processes specific to each meditation type are also supported by lateralised networks from fast-frequency bands
Cms gem detector material study for the hl-lhc
A study on the Gaseous Electron Multiplier (GEM) foil material is performed to determine the moisture diffusion rate, moisture saturation level and the effects on its mechanical properties. The study is focused on the foil contact with ambient air and moisture to determine the value of the diffusion coefficient of water in the foil material. The presence of water inside the detector foil can determine the changes in its mechanical and electrical properties. A simulated model is developed with COMSOL Multiphysics v. 4.3 [1] by taking into account the real GEM foil (hole dimensions, shapes and material), which describes the adsorption of water. This work describes the model, its experimental verification, the water diffusion within the entire sheet geometry of the GEM foil, thus gaining concentration profiles and the time required to saturate the system and the effects on the mechanical properties
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