Self‐assembly of d8 metal polypyridine systems is a well‐established approach for the creation of 1D organometallic assemblies but there are still challenges for the large‐scale construction of ...nanostructured patterns from these building blocks. We describe herein the use of high‐throughput nanoimprint lithography (NIL) to direct the self‐assembly of the bimetallic complexes 4′‐ferrocenyl‐(2,2′:6′,2′′‐terpyridine)M(OAc)+(OAc)− (M=Pd or Pt; OAc=acetate). Uniform nanorods are fabricated from the molecular self‐organization and evidenced by morphological characterization. More importantly, when top‐down NIL is coupled with the bottom‐up self‐assembly of the organometallic building blocks, regular arrays of nanorods can be accessed and the patterns can be controlled by changing the lithographic stamp, where the mold imposes a confinement effect on the nanorod growth. In addition, patterns consisting of the products formed after pyrolysis are studied. The resulting arrays of ferromagnetic FeM alloy nanorods suggest promising potential for the scalable production of ordered magnetic arrays and fabrication of magnetic bit‐patterned media.
Back in print: Top‐down lithography is coupled with bottom‐up self‐assembly. The molecular self‐assembly of bimetallic complexes to give nanoparticles is precisely controlled to prepare ordered patterns of nanoparticle assemblies with a high throughput.
In resting-state functional magnetic resonance imaging (fMRI), functional connectivity measures can be influenced by the presence of a strong global component. A widely used pre-processing method for ...reducing the contribution of this component is global signal regression, in which a global mean time series signal is projected out of the fMRI time series data prior to the computation of connectivity measures. However, the use of global signal regression is controversial because the method can bias the correlation values to have an approximately zero mean and may in some instances create artifactual negative correlations. In addition, while many studies treat the global signal as a non-neural confound that needs to be removed, evidence from electrophysiological and fMRI measures in primates suggests that the global signal may contain significant neural correlates. In this study, we used simultaneously acquired fMRI and electroencephalographic (EEG) measures of resting-state activity to assess the relation between the fMRI global signal and EEG measures of vigilance in humans. We found that the amplitude of the global signal (defined as the standard deviation of the global signal) exhibited a significant negative correlation with EEG vigilance across subjects studied in the eyes-closed condition. In addition, increases in EEG vigilance due to the ingestion of caffeine were significantly associated with both a decrease in global signal amplitude and an increase in the average level of anti-correlation between the default mode network and the task-positive network.
•Global signal amplitude (GSamp) is negatively correlated with EEG vigilance.•Caffeine-induced decreases in GSamp are related to increases in EEG vigilance.•Increases in EEG vigilance are related to increases in DMN-TPN anti-correlation.
An investigation at a major industrial facility in the Midwestern United States provides insights regarding the amount of attenuation of sub‐surface vapors occurring at industrial buildings. The ...buildings at the facility were ranked in terms of vapor intrusion potential and testing began in October 2016 and is ongoing. Results have been evaluated for data collected at 718 unique locations across 77 buildings. A total of 1646 sample pairs (sub‐slab and indoor air) have been collected and analyzed for 65 analytes, resulting in a total of 106,990 data pairs. As many as 49 sample pairs were collected within a given building during a single sampling event and up to 11 rounds of seasonal testing have been performed at selected buildings. Seasonal variability in sub‐slab soil‐gas concentrations was found to be negligible. Data analysis was performed to look for data trends across the entire data set and identify inter‐building comparisons. This data evaluation focused on individual volatile organic compounds (e.g., tetrachloroethylene, trichloroethylene) present in the sub‐slab soil gas at concentrations exceeding 1000 μg/m3. A total of 157 building‐specific attenuation coefficients (α) were evaluated. This evaluation demonstrated that large industrial buildings have a much greater attenuation than that assumed for single‐family residential buildings. All attenuation coefficient values were lower than 0.03, which is the standard regulatory default for non‐residential buildings. The median value was 9.3E‐05 and the 95% upper confidence limit was 2.7E‐04. There is some evidence of lower attenuation under wintertime conditions. The data suggests that the default attenuation factor of 0.03 over‐predicts indoor air impacts at this industrial facility by at least two orders of magnitude.
Hard ferromagnetic (L10 phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be one of the most promising candidates for the next generation of ...ultrahigh‐density data storage system. The question of how to generate ordered patterns of L10‐FePt NPs and how to transform the technology for practical applications represents a key current challenge. Here the direct synthesis of L10 phase FePt NPs by pyrolysis of Fe‐containing and Pt‐containing metallopolymer blend without post‐annealing treatment is reported. Rapid single‐step fabrication of large‐area nanodot arrays (periodicity of 500 nm) of L10‐ordered FePt NPs can also be achieved by employing the metallopolymer blend, which possesses excellent solubility in most organic solvents and good solution processability, as the precursor through nanoimprint lithography (NIL). Magnetic force microscopy (MFM) imaging of the nanodot pattern indicates that the patterned L10 phase FePt NPs are capable of exhibiting decent magnetic response, which suggests a great potential to be utilized directly in the fabrication of bit patterned media (BPM) for the next generation of magnetic recording technology.
Rapid single‐step fabrication of large‐area nanodot arrays of L10‐FePt nanoparticles (NPs) are achieved by employing a metallopolymer blend of individual Fe‐ and Pt‐containing homopolymers as the precursor through nanoimprint lithography. Imaging of the nanodot pattern indicates that the patterned NPs exhibit a decent magnetic response, which suggests potential to be utilized directly in the fabrication of bit‐patterned media for the next generation of magnetic recording technology.
Changes in vigilance or alertness during a typical resting state fMRI scan are inevitable and have been found to affect measures of functional brain connectivity. Since it is not often feasible to ...monitor vigilance with EEG during fMRI scans, it would be of great value to have methods for estimating vigilance levels from fMRI data alone. A recent study, conducted in macaque monkeys, proposed a template-based approach for fMRI-based estimation of vigilance fluctuations. Here, we use simultaneously acquired EEG/fMRI data to investigate whether the same template-based approach can be employed to estimate vigilance fluctuations of awake humans across different resting-state conditions. We first demonstrate that the spatial pattern of correlations between EEG-defined vigilance and fMRI in our data is consistent with the previous literature. Notably, however, we observed a significant difference between the eyes-closed (EC) and eyes-open (EO) conditions, finding stronger negative correlations with vigilance in regions forming the default mode network and higher positive correlations in thalamus and insula in the EC condition when compared to the EO condition. Taking these correlation maps as “templates” for vigilance estimation, we found that the template-based approach produced fMRI-based vigilance estimates that were significantly correlated with EEG-based vigilance measures, indicating its generalizability from macaques to humans. We also demonstrate that the performance of this method was related to the overall amount of variability in a subject's vigilance state, and that the template-based approach outperformed the use of the global signal as a vigilance estimator. In addition, we show that the template-based approach can be used to estimate the variability across scans in the amplitude of the vigilance fluctuations. We discuss the benefits and tradeoffs of using the template-based approach in future fMRI studies.
•Template-based approach can be used to estimate vigilance fluctuations of awake humans at rest.•The approach can be used when external vigilance monitoring (such as with EEG) is not feasible.•Performance of this method is related to the amount of variability in a subject's vigilance state.•It can be used to estimate the variability across runs in the amplitude of the vigilance fluctuations.•Template-based approach outperforms the use of the global signal as a vigilance estimator.
A polyferroplatinyne polymer can be patterned on the surface of Si wafer in ordered nanoline or nanodot shapes with PDMS molds through nanoimprint lithography (NIL), and subsequent thermal treatment ...gives rise to the nanopatterned arrays of L10‐FePt nanoparticles with the same periodicities. The method offers excellent potential to be utilized in the simple and rapid fabrication of bit patterned media for magnetic data recording.
Resting-state functional connectivity magnetic resonance imaging is proving to be an essential tool for the characterization of functional networks in the brain. Two of the major networks that have ...been identified are the default mode network (DMN) and the task positive network (TPN). Although prior work indicates that these two networks are anti-correlated, the findings are controversial because the anti-correlations are often found only after the application of a pre-processing step, known as global signal regression, that can produce artifactual anti-correlations. In this paper, we show that, for subjects studied in an eyes-closed rest state, caffeine can significantly enhance the detection of anti-correlations between the DMN and TPN without the need for global signal regression. In line with these findings, we find that caffeine also leads to widespread decreases in connectivity and global signal amplitude. Using a recently introduced geometric model of global signal effects, we demonstrate that these decreases are consistent with the removal of an additive global signal confound. In contrast to the effects observed in the eyes-closed rest state, caffeine did not lead to significant changes in global functional connectivity in the eyes-open rest state.
► Caffeine causes widespread decreases in functional connectivity. ► Caffeine reduces the global signal amplitude. ► Caffeine enhances the detection of the anti-correlations between the DMN and TPN.
The accurate regulation of the size of the ferromagnetic nanoparticle synthesized from the one-pot pyrolysis of metallopolymer is a challenging topic to date. A bimetallic complex TPy-FePd-1 was ...prepared and used as a single-source precursor to synthesize ferromagnetic FePd nanoparticles (NPs) by one-pot pyrolysis. The resultant FePd NPs have a mean particle size of 19.8 nm and show a coercivity of 1.02 kOe. In addition, the labile ligand NCMe in TPy-FePd-1 was easily substituted by a pyridyl group. A random copolymer PS-P4VP was used to coordinate with TPy-FePd-1, and the as-synthesized metallopolymer made the metal fraction disperse evenly along the flexible chain. Investigation of FePd NPs from the bimetallic polymers with different metal fractions was also made, and the size of the resultant nanoparticles could be easily controlled by tuning the metal fraction in the polymer.
A bimetallic complex TPy-FePd-1 was used as a single-source precursor to synthesize ferromagnetic FePd nanoparticles by a one-pot pyrolysis. In addition, metallopolymers with different metal fractions derived from TPy-FePd-1 were prepared and the size of FePd NPs from these polymer precursors increased linearly with the metal content. Display omitted
•Bimetallic complexes containing Fe and Pd were prepared.•Ferromagnetic FePd nanoparticles were synthesized by one-pot pyrolysis of these single-source precursors.•The size of FePd nanoparticles was tuned by controlling the ratio of the metal fraction in the precursors.
Lung cancer metastases comprise most of all brain metastases in adults and most brain metastases are diagnosed by magnetic resonance (MR) scans. The purpose of this study was to conduct an MR ...imaging-based radiomic analysis of brain metastatic lesions from patients with primary lung cancer to classify mutational status of the metastatic disease. We retrospectively identified lung cancer patients with brain metastases treated at our institution between 2009 and 2017 who underwent genotype testing of their primary lung cancer. Brain MR Images were used for segmentation of enhancing tumors and peritumoral edema, and for radiomic feature extraction. The most relevant radiomic features were identified and used with clinical data to train random forest classifiers to classify the mutation status. Of 110 patients in the study cohort (mean age 57.51 ± 12.32 years; M: F = 37:73), 75 had an EGFR mutation, 21 had an ALK translocation, and 15 had a KRAS mutation. One patient had both ALK translocation and EGFR mutation. Majority of radiomic features most relevant for mutation classification were textural. Model building using both radiomic features and clinical data yielded more accurate classifications than using either alone. For classification of EGFR, ALK, and KRAS mutation status, the model built with both radiomic features and clinical data resulted in area-under-the-curve (AUC) values based on cross-validation of 0.912, 0.915, and 0.985, respectively. Our study demonstrated that MR imaging-based radiomic analysis of brain metastases in patients with primary lung cancer may be used to classify mutation status. This approach may be useful for devising treatment strategies and informing prognosis.
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