We investigate the functioning of the ocean’s biological pump by analyzing the vertical transfer efficiency of particulate organic carbon (POC). Data evaluated include globally distributed time ...series of sediment trap POC flux, and remotely sensed estimates of net primary production (NPP) and sea surface temperature (SST). Mathematical techniques are developed to compare these temporally discordant time series using NPP and POC flux climatologies. The seasonal variation of NPP is mapped and shows regional‐ and basin‐scale biogeographic patterns reflecting solar, climatic, and oceanographic controls. Patterns of flux are similar, with more high‐frequency variability and a subtropical‐subpolar pattern of maximum flux delayed by about 5 days per degree latitude increase, coherent across multiple sediment trap time series. Seasonal production‐to‐flux analyses indicate during intervals of bloom production, the sinking fraction of NPP is typically half that of other seasons. This globally synchronous pattern may result from seasonally varying biodegradability or multiseasonal retention of POC. The relationship between NPP variability and flux variability reverses with latitude, and may reflect dominance by the large‐amplitude seasonal NPP signal at higher latitudes. We construct algorithms describing labile and refractory flux components as a function of remotely sensed NPP rates, NPP variability, and SST, which predict POC flux with accuracies greater than equations typically employed by global climate models. Globally mapped predictions of POC export, flux to depth, and sedimentation are supplied. Results indicate improved ocean carbon cycle forecasts may be obtained by combining satellite‐based observations and more mechanistic representations taking into account factors such as mineral ballasting and ecosystem structure.
Alzheimer's disease (AD) is a common neurodegenerative disease and mild cognitive impairment (MCI) is considered as the prodromal stage of AD. Previous studies showed that changes in the neurotrophin ...signaling pathway could lead to cognitive decline in AD. However, the association of single nucleotide polymorphisms (SNPs) in genes that are involved in this pathway with AD progression from MCI remains unclear.
We investigated the associations between SNPs involved in the neurotrophin signaling pathway with AD progression.
We performed single-locus analysis to identify neurotrophin-signaling-related SNPs associated with the AD progression using 767 patients from the Alzheimer's Disease Neuroimaging Initiative study and 1,373 patients from the National Alzheimer's Coordinating Center study. We constructed polygenic risk scores (PRSs) using the identified independent non-APOE SNPs and evaluated its prediction performance on AD progression.
We identified 25 SNPs significantly associated with AD progression with Bayesian false-discovery probability ≤0.8. Based on the linkage disequilibrium clumping and expression quantitative trait loci analysis, we found 6 potentially functional SNPs that were associated with AD progression independently. The PRS analysis quantified the combined effects of these SNPs on longitudinal cognitive assessments and biomarkers from cerebrospinal fluid and neuroimaging. The addition of PRSs to the prediction model for 3-year progression to AD from MCI significantly increased the predictive accuracy.
Genetic variants in the specific genes of the neurotrophin signaling pathway are predictors of AD progression. eQTL analysis supports that these SNPs regulate expression of key genes involved in the neurotrophin signaling pathway.
Atmospheric plasma sprayed (APS) Al2O3-TiO2 coatings have found a wide range of industrial application due to their favorable properties, combined with low costs and a high availability. However, the ...detailed effect of the phase composition and the element distribution of the feedstock powders on the coating properties and the spraying process have only crudely been investigated so far. Here the impact of aluminum titanate (Al2TiO5) on the microstructural features and mechanical properties of Al2O3-40 wt.% TiO2 APS coatings is demonstrated by investigating the detailed phase composition and the distribution of aluminum and titanium in three fused and crushed feedstock powders and the respective coatings. Thereby, a direct influence of Al2TiO5 content on the deposition efficiency, the porosity, the elastic modulus, and the hardness of the coatings is revealed. The results emphasize the need for a more detailed specification of commercial Al2O3-TiO2 feedstock powders to ensure a high reliability of the coating properties.
Long-term operation of Cr3C2–NiCr thermal spray coatings at elevated temperatures, including service in oxidative and corrosive environments, leads to significant changes in the coating composition ...and microstructure. A critical, but often overlooked, aspect of high temperature service conditions is interdiffusion between the coating and substrate. This leads to changes in the coating/substrate compositions and microstructures with significant consequences in terms of the functionality of the coating. The aim of this work was to characterise the magnitude and mechanism of interdiffusion between a Cr3C2–NiCr coating and a Ni-based Alloy 625 substrate at 500–900 °C for up to 30 days. Interdiffusion was not observed at 500 °C, but occurred to a limited extent at 700 °C, and very intensively at 900 °C. The precipitation of M23C6 and M6C grains within the alloy grain boundaries was proposed to occur due to carbon diffusion from the coating into the substrate. It is proposed, that this carbon was liberated from the Cr3C2 grains in the coating due to formation of (Cr,Ni)7C3. Chromium diffusion from the substrate into the coating resulted in the formation of a continuous oxide layer at the coating–substrate interface and the formation of a continuous (Cr,Ni)7C3 layer in the coating adjacent to the interfacial oxide. Loss of Cr from the substrate led to the formation of a barren, precipitate free zone adjacent to the interface.
•First systematic study of interdiffusion between a Cr3C2-25NiCr coating and Alloy 625 at 500°C, 700°C and 900°C.•Precipitation of M23C6/M6C grains in alloy grain boundaries due to C diffusion from the coating.•C was liberated from the Cr3C2 grains in the coating due to formation of (Cr,Ni)7C3.•Cr diffusion from the substrate resulted in a continuous (Cr,Ni)7C3 layer in the coating.•Loss of Cr from the substrate led to the formation of a precipitate free zone at the interface.
Cr3C2-NiCr thermal spray coatings are widely used to mitigate wear and corrosion at high temperatures. The aim of this work was to determine what minimum treatment temperature is required to ...transform the non-equilibrium as–sprayed coating composition back to an equilibrium composition, with the aim to improve the wear resistance. Cr3C2-NiCr coatings were sprayed using two HVOF techniques and a shrouded plasma spraying technique to produce samples with a broad spectrum of carbide dissolution and peritectic decomposition of Cr3C2. Shrouded plasma spraying was found to be highly effective in decreasing the carbon loss and the oxygen uptake. Differential scanning calorimetry (DSC) was used to characterize the exothermic solid-state phase transformations within the coatings. For the HVOF coatings, one main exothermic peak was observed, which was attributed to the crystallization of the metastable Ni binder material. In the plasma spray coating an additional higher temperature peak was also observed. This was attributed to the transformation of (Cr,Ni)7C3 and a high Cr content Ni phase, into the equilibrium phases Cr3C2 and a low Cr content Ni binder.
•New insights of heat treatment effects on Cr3C2-NiCr thermal spray coatings.•Cr3C2 undergoes dissolution/peritectic decomposition depending on spray process.•Shrouded plasma spraying effectively decreases carbon loss and oxygen uptake.•Equilibrium phases Cr3C2 and NiCr were found after 620 °C for the HVOF coating.•Treatment at 780 °C required for plasma spray coating to form equilibrium phases.
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•Titanium carbonitride is abundant, light, non-strategic and environmentally acceptable.•Titanium carbonitride grains improve the tribocorrosion performance of 316L.•Fine grained hard ...phases attained due to low interaction with the binder alloy.•Passivity of 316L is maintained despite the presence of the hard phases.•Wear-accelerated corrosion in saline environment reduced over 30 fold.
316L stainless steel has recently gained relevance as metal for additive manufacturing thanks to its high versatility in many laser deposition processes combined with its excellent mechanical and corrosion properties. However, its use in oil & gas, marine or biomedical applications is limited by its poor tribocorrosion performance, since it is prone to wear-accelerated corrosion. On the quest for extending the applicability of 316L components deposited by laser processes to tribocorrosion applications, the present work develops 316L laser claddings reinforced with titanium carbonitride grains. An agglomerated and sintered (Ti,Mo)(C,N)-Ni powder was designed for preserving the chemical integrity of the hard phases during the laser deposition process. This results in 316L composites with homogeneously distributed titanium carbonitride reinforcements with a size ranging from sub-micrometre up to about 2 µm. These 316L composites improve the tribocorrosion performance in artificial seawater by over 10 fold in open circuit potential conditions and over 30 fold at an applied passive potential. The passivity of the 316L composites is maintained even though of a lower break down potential. These results highlight the enormous potential of 316L reinforced with titanium carbonitride deposited by laser processes for wear resistant components operating in saline environments.
Background
Short structural variants (SSVs), including insertions/deletions (indels), are common in the human genome and impact disease risk. The role of SSVs in late‐onset Alzheimer's disease (LOAD) ...has been understudied. In this study, we developed a bioinformatics pipeline of SSVs within LOAD–genome‐wide association study (GWAS) regions to prioritize regulatory SSVs based on the strength of their predicted effect on transcription factor (TF) binding sites.
Methods
The pipeline utilized publicly available functional genomics data sources including candidate cis‐regulatory elements (cCREs) from ENCODE and single‐nucleus (sn)RNA‐seq data from LOAD patient samples.
Results
We catalogued 1581 SSVs in candidate cCREs in LOAD GWAS regions that disrupted 737 TF sites. That included SSVs that disrupted the binding of RUNX3, SPI1, and SMAD3, within the APOE‐TOMM40, SPI1, and MS4A6A LOAD regions.
Conclusions
The pipeline developed here prioritized non‐coding SSVs in cCREs and characterized their putative effects on TF binding. The approach integrates multiomics datasets for validation experiments using disease models.
This work reveals the influence of heat treatments on the microstructure, mechanical properties and abrasive wear behaviour of a Cr3C2NiCr coating deposited by an ethene-fuelled high-velocity ...oxygen-fuel spray process using an agglomerated-and-sintered feedstock powder. The wear resistance of an as-sprayed and heat treated (8h at 800°C) coating was evaluated in low- and high-stress abrasion regimes, the latter in a temperature range up to 800°C. Precipitation of secondary carbides from the supersaturated as-sprayed binder matrix is at the core of the observed changes in the coatings wear resistance upon heat treating. This aging process renders the binder matrix softer and more ductile, as was probed by means of nanoindentation, and thereby improves its resistance against micro-cracking which is identified as an important wear mechanism in high-stress abrasion conditions.
•Tailoring the fracture toughness by heat-induced secondary carbide precipitation.•Increase of high-stress abrasive wear resistance for moderate temperature applications.
Mild cognitive impairment (MCI) is a heterogeneous condition and MCI patients are at increased risk of progression to dementia due to Alzheimer's disease (AD).
In this study, we aim to evaluate the ...associations between polygenic risk scores (PRSs) and 1) time to AD progression from MCI, 2) changes in longitudinal cognitive impairment, and 3) biomarkers from cerebrospinal fluid and imaging.
We constructed PRS by using 40 independent non-APOE SNPs from well-replicated AD GWASs and tested its association with the progression time from MCI to AD by using 767 MCI patients from the ADNI study and 1373 patients from the NACC study. PRSs calculated with other methods were also computed.
We found that the PRS constructed with SNPs that reached genome-wide significance predicted the progression from MCI to AD (beta = 0.182, SE = 0.061, p = 0.003) after adjusting for the demographic and clinical variables. This association was replicated in the NACC dataset (beta = 0.094, SE = 0.037, p = 0.009). Further analyses revealed that PRS was associated with the increased ADAS-Cog11/ADAS-Cog13/ADASQ4 scores, tau/ptau levels, and cortical amyloid burdens (PiB-PET and AV45-PET), but decreased hippocampus and entorhinal cortex volumes (p < 0.05). Mediation analysis showed that the effect of PRS on the increased risk of AD may be mediated by Aβ42 (beta = 0.056, SE = 0.026, p = 0.036).
Our findings suggest that PRS can be useful for the prediction of time to AD and other clinical changes after the diagnosis of MCI.
•Motor evoked potential amplitudes may be small and difficult to monitor during surgery in some patients.•Tetanic stimulation of peripheral nerves improves motor evoked potential amplitudes.•Tetanic ...stimulation can also be used in patient with myelopathy and peripheral neuropathy, with some cautions.
Tetanic stimulation of a peripheral nerve prior to transcranial electrical stimulation (TES) may enhance motor evoked potential (MEP) amplitudes. The purpose of this study was to investigate the post-tetanic MEP (p-MEP) technique in improving MEP amplitudes.
Conventional TES MEPs (c-MEP) and p-MEPs with left upper limb stimulation (p-MEPUL) or left lower limb stimulation (p-MEPLL) were performed in 26 patients. Bilateral hand and foot MEP amplitudes obtained with each protocol were compared. Subgroup comparisons were performed for myelopathy and peripheral neuropathy patients. Within-subject amplitude differences between c-MEP and each p-MEP technique were compared using a Wilcoxon test.
The mean age of the patients was 52.7 years (range, 12–79 years). Overall, p-MEPUL resulted in MEP improvement in 25 of 26 (96%) patients, and p-MEPLL improved MEPs in 19 of 26 (73%) patients. The increase in MEP amplitudes were statistically significant in all muscle groups except left foot. Similar improvements were seen in the myelopathy group; in the neuropathy group, p-MEPUL produced similar results, but p-MEPLL did not.
The p-MEP technique can improve MEP amplitudes, including in patients with myelopathy. In patients with peripheral neuropathy, the results were mixed.
Tetanic stimulation can enhance intraoperative MEP amplitudes.
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