SnSethermal conductivity from optothermal Raman and Stokes/anti-Stokes thermometry.

The optothermal Raman method is useful in determining the in-plane thermal conductivity of two-dimensional (2D) materials that are either suspended or supported on a substrate. We compare this method with the Stokes/anti-Stokes scattering thermometry method, which can play a role in both calibration of Raman peak positions as well as extraction of the local phonon temperature. This work demonstrates that the Stokes/anti-Stokes intensity ratio plays an important role in determining the in-plane thermal conductivity of 2D tin diselenide (SnSe) dry-transferred onto a polished copper (Cu) substrate.

Enabling Oxidation Protection and Carrier-Type Switching for Bismuth Telluride Nanoribbons via Organic Molecule Coating.

Thermoelectric materials with high electrical conductivity and low thermal conductivity (e.g., BiTe) can efficiently convert waste heat into electricity; however, in spite of favorable theoretical predictions, individual BiTe nanostructures tend to perform less efficiently than bulk BiTe.

Tuning of the electronic and vibrational properties of epitaxial MoSthrough He-ion beam modification.

Atomically thin transition metal dichalcogenides (TMDs), like MoSwith high carrier mobilities and tunable electron dispersions, are unique active material candidates for next generation opto-electronic devices. Previous studies on ion irradiation show great potential applications when applied to two-dimensional (2D) materials, yet have been limited to micron size exfoliated flakes or smaller. To demonstrate the scalability of this method for industrial applications, we report the application of relatively low power (50 keV)Heion irradiation towards tuning the optoelectronic properties of an epitaxially grown continuous film of MoSat the wafer scale, and demonstrate that precise manipulation of atomistic defects can be achieved in TMD films using ion implanters.

Use of Transmission Electron Microscopy for Analysis of Aerosol Particles and Strategies for Imaging Fragile Particles.

For over 25 years, transmission electron microscopy (TEM) has provided a method for the study of aerosol particles with sizes from below the optical diffraction limit to several microns, resolving the particles as well as smaller features. The wide use of this technique to study aerosol particles has contributed important insights about environmental aerosol particle samples and model atmospheric systems. TEM produces an image that is a 2D projection of aerosol particles that have been impacted onto grids and, through associated techniques and spectroscopies, can contribute additional information such as the determination of elemental composition, crystal structure, and 3D particle structures.

Dynamics of Liquid-Liquid Phase Separation in Submicrometer Aerosol.

Nanoscale materials, when compared to their bulk components, possess unique properties. In particular, shifts in phase transitions can occur for submicrometer particles. For instance, small particles do not undergo the process of liquid-liquid phase separation (LLPS).

Flash Freeze Flow Tube to Vitrify Aerosol Particles at Fixed Relative Humidity Values.

Development of methods to measure the phase transitions and physical properties of submicron atmospheric aerosol particles is needed to better model these systems. In this paper, we present a method to flash freeze submicron particles to measure phase transitions as a function of relative humidity (RH). Particles are equilibrated at a fixed RH, vitrified in a temperature-controlled flow tube, and imaged with cryogenic transmission electron microscopy (cryo-TEM).

Size-Dependent Liquid-Liquid Phase Separation in Atmospherically Relevant Complex Systems.

Physical properties of aerosol particles, such as liquid-liquid phase separation (LLPS), have the potential to impact the climate system. Model systems have been shown to have size-dependent LLPS in the submicron regime; however, these systems are an extreme simplification of ambient aerosol, which can include myriad organic compounds. We expand the studies of LLPS in particles consisting of ammonium sulfate and more complex organic mixtures from multiple organic compounds to α-pinene secondary organic matter (SOM).

In vivo TSPO imaging in patients with multiple sclerosis: a brain PET study with [18F]FEDAA1106.

Background: The activation of microglia, in general, and the upregulation of the translocator protein (18 kDa) (TSPO) system, in particular, are key features of neuroinflammation, of which the in vivo visualization and quantitative assessment are still challenging due to the lack of appropriate molecular imaging biomarkers. Recent positron emission tomography (PET) studies using TSPO radioligands such as [11C]PK11195 and [11C]PBR28 have indicated the usefulness of these PET biomarkers in patients with neuroinflammatory diseases, including multiple sclerosis (MS). [18F]FEDAA1106 is a recently developed PET radioligand for the in vivo quantification of TSPO.

Association of N-acetylaspartate and cerebrospinal fluid Aβ42 in dementia.

The interplay of amyloid and mitochondrial function is considered crucial in the pathophysiology of Alzheimer's disease (AD). We tested the association of the putative marker of mitochondrial function N-acetylaspartate (NAA) as measured by proton magnetic resonance spectroscopy within the medial temporal lobe and cerebrospinal fluid amyoid-β42 (Aβ42), total Tau and pTau181. 109 patients were recruited in a multicenter study (40 mild AD patients, 14 non-AD dementia patients, 29 mild cognitive impairment (MCI) AD-type patients, 26 MCI of non-AD type patients).

Macromolecule content influences proton diffusibility in gliomas.

Objectives: Different compositions of the extra cellular matrix with changing concentrations of more or less hydrophilic components like proteins may have a major influence on the diffusion phenomena found in gliomas.

Methods: 24 patients (14 male / 10 female) with histologically confirmed non necrotic glioma underwent preoperative MRI, including magnetisation transfer (MTR), triple echo T2 weighted (T2W) and diffusion weighted (DWI) sequences. Apparent diffusion coefficient (ADC), quantitative T2 and MTR maps were calculated and regions of interest (ROIs) were placed in the tumour centre (TU) and in the contralateral hemisphere (NWM).

Interrater agreement for final infarct MRI lesion delineation.

Background And Purpose: Lesion volume measured on follow-up magnetic resonance imaging (MRI) is commonly used as an outcome parameter in clinical stroke trials. However, few studies have evaluated the optimal sequence choice and the interrater reliability of this outcome measure. The objective of this study was to quantify the geometric interrater agreement for lesion delineation of chronic infarcts on T2-weighted and fluid-attenuated inverse recovery (FLAIR) MRI.

AGC1 deficiency associated with global cerebral hypomyelination.

The mitochondrial aspartate-glutamate carrier isoform 1 (AGC1), specific to neurons and muscle, supplies aspartate to the cytosol and, as a component of the malate-aspartate shuttle, enables mitochondrial oxidation of cytosolic NADH, thought to be important in providing energy for neurons in the central nervous system. We describe AGC1 deficiency, a novel syndrome characterized by arrested psychomotor development, hypotonia, and seizures in a child with a homozygous missense mutation in the solute carrier family 25, member 12, gene SLC25A12, which encodes the AGC1 protein. Functional analysis of the mutant AGC1 protein showed abolished activity.

Imaging in acute stroke--a personal view.

Acute stroke imaging has developed from intraarterial angiography and native, unenhanced CT to highly elaborated tools with the access to a variety of pathophysiological variables ahead of therapy. Despite enduring unresolved problems, we can now obtain a comprehensive view on the individual patient's disease and act fast and specifically under consideration of chances and risks of different therapies. The stroke neuroradiologist is the decisive partner of engaged clinical disciplines and should own a leading role in future acute stroke trials.

Combination of T2*W and FLAIR abnormalities for the prediction of parenchymal hematoma following thrombolytic therapy in 100 stroke patients.

Introduction: The objective of our study was to determine whether the combination of hypointense spots ("cerebral microbleeds," CMBs) with a leukoaraiosis is associated with the risk of parenchymal hematoma (PH) after thrombolytic therapy.

Patients And Methods: We analyzed magnetic resonance imaging (MRI) scans acquired within 6 hours after symptom onset from 100 ischemic stroke patients. Multiparametric MRI including a T2*-weighted (T2*w) MRI and fluid attenuated inversion recovery (FLAIR) was performed before thrombolysis in all patients.

A multicenter (1)H-MRS study of the medial temporal lobe in AD and MCI.

Objective: The need for biological markers of Alzheimer disease (AD) is constantly increasing. Proton magnetic resonance spectroscopy ((1)H-MRS) studies have provided consistent evidence for a reduction of the neuronal marker N-acetylaspartate (NAA) in patients with AD. Within the German Competence Network on Dementia, we conducted a (1)H-MRS study in patients with mild dementia and mild cognitive impairment (MCI) at four sites to investigate the multicenter feasibility of (1)H-MRS.

Comparison of 10 perfusion MRI parameters in 97 sub-6-hour stroke patients using voxel-based receiver operating characteristics analysis.

Background And Purpose: Perfusion-weighted imaging can predict infarct growth in acute stroke and potentially be used to select patients with tissue at risk for reperfusion therapies. However, the lack of consensus and evidence on how to best create PWI maps that reflect tissue at risk challenges comparisons of results and acute decision-making in trials. Deconvolution using an arterial input function has been hypothesized to generate maps of a more quantitative nature and with better prognostic value than simpler summary measures such as time-to-peak or the first moment of the concentration time curve.

T2' imaging predicts infarct growth beyond the acute diffusion-weighted imaging lesion in acute stroke.

Purpose: To show that measurement of the transverse relaxation time that characterizes signal loss caused by local susceptibilities (T2') is sensitive to an increased deoxyhemoglobin concentration in the brain, indicating tissue at risk for infarction.

Materials And Methods: The study was approved by the local institutional review board; patients or their guardians provided informed consent. Magnetic resonance (MR) imaging was performed within 6 hours of symptom onset and again 1-11 days thereafter in 100 consecutive stroke patients, all of whom received intravenous thrombolytic therapy (mean age, 67 years).

[Visual rating of T2'-blood-oxygen-level-dependent magnetic resonance imaging in acute stroke patients--a pilot study].

Purpose: Delineation of brain tissue that is at risk but not yet infarcted (penumbra) continues to be a major challenge for stroke imaging. Metabolic characterization of the penumbra might be able to be achieved using blood-oxygen-level-dependent (BOLD) imaging.

Materials And Methods: We analyzed MRI data from 20 patients within the first 6 hours after stroke onset and after 5-8 days.

Leukoaraiosis is a risk factor for symptomatic intracerebral hemorrhage after thrombolysis for acute stroke.

Background And Purpose: The aim of the study was to evaluate whether leukoaraiosis (LA) is a risk factor for symptomatic intracerebral hemorrhage (sICH) in patients treated with thrombolysis for acute stroke.

Methods: In this retrospective, multicenter analysis, we evaluated data from acute anterior circulation stroke patients (n=449; <6 hours after symptom onset) treated with thrombolysis. All patients had received standard magnetic resonance imaging evaluation before thrombolysis, including a high-quality T2-weighted sequence.

Disarrangement of fiber tracts and decline of neuronal density correlate in glioma patients--a combined diffusion tensor imaging and 1H-MR spectroscopy study.

Background And Purpose: Diffusion tensor imaging (DTI) and MR spectroscopy are noninvasive, quantitative tools for the preoperative assessment of gliomas with which the quantitative parameter fractional anisotropy (FA) and the concentration of neurometabolites N-acetylaspartate (NAA), choline (Cho), creatine (Cr) of the brain can be determined. Measurements of FA and NAA reflect the integrity of fiber tracts and the presence of neurons, respectively. This investigation examines changes of FA and NAA and compares these different aspects in architecture of gliomas after spatial coregistration.