Structure of CdTe/ZnTe superlattices

The structure of CdTe/ZnTe superlattices has been analyzed through θ/2θ x‐ray diffraction, photoluminescence, and in situ reflection high‐energy electron diffraction (RHEED) measurements. Samples are found to break away from Cd_(x)Zn_(1−x)Te buffer layers as a consequence of the 6% lattice mismatch in this system. However, defect densities in these superlattices are seen to drop dramatically away from the buffer layer interface, accounting for the intense photoluminescence and high‐average strain fields seen in each of our samples. Observed variations in residual strains suggest that growth conditions play a role in forming misfit defects. This could explain discrepancies with calculated values of critical thickness based on models which neglect growth conditions. Photoluminescence spectra reveal that layer‐to‐layer growth proceeded with single monolayer uniformity, suggesting highly reproducible growth. Our results give hope for relatively defect‐free Cd_(x)Zn_(1−x)Te/Cd_(y)Zn_(1−y)Te superlattices with the potential for applications to optoelectronics offered by intense visible light emitters

A new MBE CdTe photoconductor array detector for X-ray applications

A CdTe photoconductor array x-ray detector was grown using Molecular Beam Epitaxially (MBE) on a Si (100) substrate. The temporal response of the photoconductor arrays is as fast as 21 psec risetime and 38 psec Full Width Half Maximum (FWHM). Spatial and energy responses were obtained using x-rays from a rotating anode and synchrotron radiation source. The spatial resolution of the photoconductor was good enough to provide 75 {micro}m FWHM using a 50 {micro}m synchrotron x-ray beam. A substantial number of x-ray photons are absorbed effectively within the MBE CdTe layer as observed from the linear response up to 15 keV. These results demonstrate that MBE grown CdTe is a suitable choice of the detector materials to meet the requirements for x-ray detectors in particular for the new high brightness synchrotron sources

Direct observation of threading dislocations in GaN by high-resolution Z-contrast imaging

Wide gap nitride semiconductors have attracted significant attention recently due to their promising performance as short-wavelength light emitting diodes (LEDs) and blue lasers. One interesting issue concerning GaN is that the material is relatively insensitive to the presence of a density of dislocations which is six orders of magnitude higher than that for III-V arsenide and phosphide based LEDs. Although it is well known that these dislocations originate at the film-substrate interface during film growth, thread through the whole epilayer with line direction along and are perfect dislocations with Burgers vectors of a, c, or c+a, the reason why they have such a small effect on the properties of GaN is unclear. To develop a fundamental understanding of the properties of these dislocations, the core structures are studied here by high resolution Z-contrast imaging in a 300kV VG HB603 scanning transmission electron microscope (STEM) with a resolution of 0.13 nm. As the Z-contrast image is a convolution between the probe intensity profile and the specimen object function, it is possible to obtain more detailed information on the specimen object function, i.e. the structure, through maximum entropy analysis (the maximum entropy technique produces the ``most likely`` object function which is consistent with the image)

Heart-Type Fatty Acid-Binding Protein Predicts Long-Term Mortality and Re-Infarction in Consecutive Patients With Suspected Acute Coronary Syndrome Who Are Troponin-Negative

ObjectivesThe purpose of this study was to establish the prognostic value of measuring heart fatty acid-binding protein (H-FABP) in patients with suspected acute coronary syndrome (ACS) (in particular, low- to intermediate-risk patients), in addition to troponin measured with the latest third-generation troponin assay.BackgroundWe have previously shown that H-FABP is a useful prognostic marker in patients with proven ACS.MethodsPatients (n = 1,080) consecutively admitted to the hospital with suspected ACS were recruited over 46 weeks. Siemens Advia Ultra-TnI (Siemens Healthcare Diagnostics, Newbury, United Kingdom) and Randox Evidence H-FABP (Randox Laboratories, Ltd., Co., Antrim, United Kingdom) were analyzed on samples collected 12 to 24 h from symptom onset. After exclusion of patients with ST-segment elevation and new left bundle branch block, 955 patients were included in the analysis.ResultsThe primary outcome measure of death or readmission with myocardial infarction after a minimum follow-up period of 12 months (median 18 months) occurred in 96 of 955 patients (10.1%). The H-FABP concentration was an independent predictor of death or myocardial infarction, after multivariate adjustment. Patients with H-FABP concentrations >6.48 μg/l had significantly increased risk of adverse events (adjusted hazard ratio: 2.62, 95% confidence interval: 1.30 to 5.28, p = 0.007). Among troponin-negative patients (which constituted 79.2% of the cohort), the aforementioned cutoff of 6.48 μg/l identified patients at very high risk for adverse outcomes independent of patient age and serum creatinine.ConclusionsWe have demonstrated that the prognostic value of elevated H-FABP is additive to troponin in low- and intermediate-risk patients with suspected ACS. Other studies suggest that our observations reflect the value of H-FABP as a marker of myocardial ischemia, even in the absence of frank necrosis

Journal of nanobiotechnology

BACKGROUND: Nanosuspensions are an important class of delivery system for vaccine adjuvants and drugs. Previously, we developed a nanosuspension consisting of the synthetic TLR4 ligand glucopyranosyl lipid adjuvant (GLA) and dipalmitoyl phosphatidylcholine (DPPC). This nanosuspension is a clinical vaccine adjuvant known as GLA-AF. We examined the effects of DPPC supplier, buffer composition, and manufacturing process on GLA-AF physicochemical and biological activity characteristics. RESULTS: DPPC from different suppliers had minimal influence on physicochemical and biological effects. In general, buffered compositions resulted in less particle size stability compared to unbuffered GLA-AF. Microfluidization resulted in rapid particle size reduction after only a few passes, and 20,000 or 30,000 psi processing pressures were more effective at reducing particle size and recovering the active component than 10,000 psi. Sonicated and microfluidized batches maintained good particle size and chemical stability over 6 months, without significantly altering in vitro or in vivo bioactivity of GLA-AF when combined with a recombinant malaria vaccine antigen. CONCLUSIONS: Microfluidization, compared to water bath sonication, may be an effective manufacturing process to improve the scalability and reproducibility of GLA-AF as it advances further in the clinical development pathway. Various sources of DPPC are suitable to manufacture GLA-AF, but buffered compositions of GLA-AF do not appear to offer stability advantages over the unbuffered composition

Material quality characterization of CdZnTe substrates for HgCdTe epitaxy

Cd1-xZnxTe (CZT) substrates were studied to investigate their bulk and surface properties. Imperfections in CZT substrates affect the quality of Hg1-xCdxTe (MCT) epilayers deposited on them and play a role in limiting the performance of infrared (IR) focal plane arrays. CZT wafers were studied to investigate their bulk and surface properties. Transmission and surface x-ray diffraction techniques, utilizing both a conventional closed-tube x-ray source as well as a synchrotron radiation source, and IR transmission microspectroscopy, were used for bulk and surface investigation. Synchrotron radiation offers the capability to combine good spatial resolution and shorter exposure times than conventional x-ray sources, which allows for high-resolution mapping of relatively large areas in an acceptable amount of time. Information on the location of grain boundaries and precipitates was also obtained. The ultimate goal of this work is to understand the defects in CZT substrates and their effects on the performance and uniformity of MCT epilayers and then to apply this understanding to produce better infrared detectors

A novel allosteric modulator of the cannabinoid CB1 receptor ameliorates hyperdopaminergia endophenotypes in rodent models

Funding and disclosure The authors declare the following financial and biomedical conflict of interests: Ruth A. Ross, Catharine A. Mielnik, Amy J. Ramsey, Iain R. Greig, Laurent A. Trembleau, Mostafa H. Abdelrahman are co-inventors on a patent application related to ABM300 and structural analogs. Kim S. Sugamori, David B. Finlay, Hayley H.A. Thorpe, Matthieu Schapira, Nirunthan Sivananthan, Chun Kit Li, Vincent M. Lam, Sean Harrington, W. McIntyre Burnham, Jibran Y. Khokhar, Ali Salahpour, Michelle Glass reported no biomedical financial interests or potential conflicts of interest. W. McIntyre Burnham received Δ9- (THC) as a gift from MedReleaf. The authors would like to gratefully acknowledge Wendy Horsfall for mouse colony maintenance. The work was funded by grants to RAR from CIHR (PPP-125784, PP2-139101), CIHR funding to AJR (MOP119298) and CIHR funding to AS (PJT-15619).Peer reviewedPostprintPublisher PD

Analysis of blood and nasal epithelial transcriptomes to identify mechanisms associated with control of SARS-CoV-2 viral load in the upper respiratory tract

Objectives: The amount of SARS-CoV-2 detected in the upper respiratory tract (URT viral load) is a key driver of transmission of infection. Current evidence suggests that mechanisms constraining URT viral load are different from those controlling lower respiratory tract viral load and disease severity. Understanding such mechanisms may help to develop treatments and vaccine strategies to reduce transmission. Combining mathematical modelling of URT viral load dynamics with transcriptome analyses we aimed to identify mechanisms controlling URT viral load. Methods: COVID-19 patients were recruited in Spain during the first wave of the pandemic. RNA sequencing of peripheral blood and targeted NanoString nCounter transcriptome analysis of nasal epithelium were performed and gene expression analysed in relation to paired URT viral load samples collected within 15 days of symptom onset. Proportions of major immune cells in blood were estimated from transcriptional data using computational differential estimation. Weighted correlation network analysis (adjusted for cell proportions) and fixed transcriptional repertoire analysis were used to identify associations with URT viral load, quantified as standard deviations (z-scores) from an expected trajectory over time. Results Eighty-two subjects (50% female, median age 54 years (range 3–73)) with COVID-19 were recruited. Paired URT viral load samples were available for 16 blood transcriptome samples, and 17 respiratory epithelial transcriptome samples. Natural Killer (NK) cells were the only blood cell type significantly correlated with URT viral load z-scores (r = −0.62, P = 0.010). Twenty-four blood gene expression modules were significantly correlated with URT viral load z-score, the most significant being a module of genes connected around IFNA14 (Interferon Alpha-14) expression (r = −0.60, P = 1e-10). In fixed repertoire analysis, prostanoid-related gene expression was significantly associated with higher viral load. In nasal epithelium, only GNLY (granulysin) gene expression showed significant negative correlation with viral load. Conclusions: Correlations between the transcriptional host response and inter-individual variations in SARS-CoV-2 URT viral load, revealed many molecular mechanisms plausibly favouring or constraining viral replication. Existing evidence corroborates many of these mechanisms, including likely roles for NK cells, granulysin, prostanoids and interferon alpha-14. Inhibition of prostanoid production and administration of interferon alpha-14 may be attractive transmission-blocking interventions