•The micro-mesopore structure characteristics of coals were measured by the LP-N2GA and CDA.•The development degree of micro-mesoporous structure in medium-rank coal was not synchronous.•The effect ...of mesoporous structure and BET SSA on gas adsorption capacity was weaker than microporous structure.
The relationship between micro-mesoporous structure characteristics and gas adsorption capacity of medium-rank coal under different particle sizes was studied by physical adsorption method. The results showed that the capacity of adsorption nitrogen and carbon dioxide, specific surface area (SSA), BET SSA and micropore volume all increased with the decrease of particle size. The range of mesoporous aperture measured by BJH method was larger than that by DFT method, but the pore volume (PV) and SSA are relatively lower, which confirmed that the BJH method will underestimate part of the aperture. However, there was blank bands in the measurement of pore size in 2–4 nm by DFT method, which will also reduce the real value. The limiting gas adsorption volumes of 1#, 2#, 3# and 4# coal samples under different particle sizes were 17.19–20.76 m3/t, 14.11–19.3 m3/t, 17.17–19.14 m3/t and 12.11–15.59 m3/t, respectively, and the results gradually increased with the decrease of particle size. The linear correlation between BET SSA, mesoporous PV and Langmuir volume of coal was 0.43, 0.5–0.53 and 0.37–0.5, respectively, which was relatively low on the whole and slightly lower than the results in the literature. The linear correlation between Langmuir volume and micropore volume and SSA was 0.73 and 0.76, respectively, which was higher than mesoporous structure parameters and BET SSA. The control effect of microporous structure parameters on gas adsorption was significantly higher than mesoporous structure and BET SSA. The error between the calculated limit gas adsorption volume and the experimental limit gas adsorption volume was small, and the proportion of the microporous filling limit gas adsorption volume was as high as 99.7%. Multiple studies have proved that micropore is the main space of gas adsorption.
Abstract Introduction Lumbar puncture (LP) is increasingly performed in memory clinics. We investigated patient-acceptance of LP, incidence of and risk factors for post-LP complications in memory ...clinic populations. Methods We prospectively enrolled 3868 patients (50% women, age 66 ± 11 years, mini mental state examination 25 ± 5) at 23 memory clinics. We used logistic regression analysis using generalized estimated equations to investigate risk factors for post-LP complications, such as typical postlumbar puncture headache (PLPH) and back pain. Results A total of 1065 patients (31%) reported post-LP complaints; 589 patients (17%) reported back pain, 649 (19%) headache, of which 296 (9%) reported typical PLPH. Only few patients needed medical intervention: 11 (0.3%) received a blood patch, 23 (0.7%) were hospitalized. The most important risk factor for PLPH was medical history of headache. An atraumatic needle and age >65 years were preventive. Gender, rest after LP, or volume of cerebrospinal fluid had no effect. Discussions The overall risk of complications is relatively low. If risk factors shown in this study are taken into account, LPs can be safely performed in memory clinics.
Lipoprotein(a) Lp(a) is a source of residual risk in patients with atherosclerotic cardiovascular disease (ASCVD). Clinical trials of fully human monoclonal antibodies targeting proprotein convertase ...subtilisin kexin 9 have shown that reductions in Lp(a) concentrations may be a predictor of event reduction with this class of cholesterol-lowering therapy. With the advent of selective therapies targeting Lp(a) such as antisense oligonucleotides, small-interfering RNA–based therapies, and gene editing, lowering of Lp(a) may lead to reduction in ASCVD. The phase 3 Lp(a)HORIZON (Assessing the Impact of Lipoprotein(a) Lowering with TQJ230 on Major Cardiovascular Events in Patients With CVD) outcomes trial is currently testing the effect of pelacarsen, an antisense oligonucleotide, on ASCVD risk. Olpasiran is a small-interfering RNA that is in a phase 3 clinical trial. As these therapies enter clinical trials, challenges in trial design will have to be addressed to optimize patient selection and outcomes.
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•Elevated Lp(a), despite treatment with statins and PCSK9i, raises the residual risk of ASCVD, driven mainly by Lp(a)-induced inflammation and oxidized phospholipids.•Antisense oligonucleotides and mRNA inhibitors targeting hepatic synthesis of apolipoprotein(a) have been developed and are currently under investigation in clinical trials, and other therapeutics utilizing CRISPR-Cas9 technology are on the horizon.•As future clinical trials are designed, challenges include defining target populations, effect size, and endpoint selection.
It is known that the Lp-curvature of a smooth, strictly convex body in Rn is constant only for origin-centered balls when 1≠p>−n, and only for balls when p=1. If p=−n, then the L−n-curvature is ...constant only for origin-symmetric ellipsoids. We prove ‘local’ and ‘global’ stability versions of these results. For p≥1, we prove a global stability result: if the Lp-curvature is almost a constant, then the volume symmetric difference of K˜ and a translate of the unit ball B is almost zero. Here K˜ is the dilation of K with the same volume as the unit ball. For 0≤p<1, we prove a similar result in the class of origin-symmetric bodies in the L2-distance. In addition, for −n<p<0, we prove a local stability result: There is a neighborhood of the unit ball that any smooth, strictly convex body in this neighborhood with ‘almost’ constant Lp-curvature is ‘almost’ the unit ball. For p=−n, we prove a global stability result in R2 and a local stability result for n>2 in the Banach-Mazur distance.
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•Eleven coals (Vdaf from 7.45% to 51.18%) were examined by LP-N2GA and SEM.•Pore shape from LP-N2GA was verified by SEM.•PSDs of mesopore are multi-modal, whereas, the micropore ...structure appears to be unimodal.•For coals of lower metamorphism (Vdaf>15%), Vdaf has little impact on micropore structure.
Eleven coal samples of different metamorphism are studied with regard to their pore structures. Both low-pressure nitrogen gas adsorption (LP-N2GA) and scanning electron microscopy (SEM) were performed. The use of these techniques allows us to gain clearer insight into the nature of the pore structure including the pore volume, specific area, pore size distribution (PSD) and pore shape. The LP-N2GA isotherms demonstrate strong differences in gas adsorption capacity between the coal samples studied, consistent with variability in specific surface area (SSA) of the samples. Pore geometry of coals with different metamorphism varies a lot, indicative of heterogeneity on coal surface, which was verified with SEM observation. Adsorption analysis revealed that mesopore size distributions are multi-modal, whereas, the micropore structure of the samples tested appears to be unimodal, with a major peak between 1.6 and 2.0nm. The influence of coal rank on pore structure was also analyzed. The U-shape relationship between mesopore SSA and Vdaf is observed, demonstrating that the number of mesopores within the lower rank coals (Vdaf>15%) decreases with increasing coal rank and the coalification mainly affects the mesopore structure. For the higher rank coals with Vdaf<15%, as the coalification effect increases, the mesopore size diminishes and the number of micropores ascends. Smaller mesopores and micropores gradually become the dominant roles. This phenomenon is due to the effect of intensive compaction within the coal bulk. The combination of LP-N2GA and SEM techniques gives a better understanding of pore characteristics in coal. The research results will provide guidance for the gas control in coal mines.
This paper proposes several principal component analysis (PCA) methods based on Lp-norm optimization techniques. In doing so, the objective function is defined using the Lp-norm with an arbitrary p ...value, and the gradient of the objective function is computed on the basis of the fact that the number of training samples is finite. In the first part, an easier problem of extracting only one feature is dealt with. In this case, principal components are searched for either by a gradient ascent method or by a Lagrangian multiplier method. When more than one feature is needed, features can be extracted one by one greedily, based on the proposed method. Second, a more difficult problem is tackled that simultaneously extracts more than one feature. The proposed methods are shown to find a local optimal solution. In addition, they are easy to implement without significantly increasing computational complexity. Finally, the proposed methods are applied to several datasets with different values of p and their performances are compared with those of conventional PCA methods.
Inflammation and oxidative stress conditions lead to a variety of oxidative modifications of lipoprotein phospholipids implicated in the occurrence and development of atherosclerotic lesions. ...Lipoprotein‐associated phospholipase A2 (Lp‐PLA2) is established as an independent risk biomarker of atherosclerosis‐related cardiovascular disease (ASCVD) and mediates vascular inflammation through the regulation of lipid metabolism in the blood and in atherosclerotic lesions. Lp‐PLA2 is associated with low‐ and high‐density lipoproteins and Lipoprotein (a) in human plasma and specifically hydrolyzes oxidized phospholipids involved in oxidative stress modification. Several oxidized phospholipids (OxPLs) subspecies can be detoxified through enzymatic degradation by Lp‐PLA2 activation, forming lysophospholipids and oxidized non‐esterified fatty acids (OxNEFAs). Lysophospholipids promote the expression of adhesion molecules, stimulate cytokines production (TNF‐α, IL‐6), and attract macrophages to the arterial intima. The present review article discusses new data on the functional roles of OxPLs and Lp‐PLA2 associated with lipoproteins.
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•Fractal characteristics of coals were analyzed using SEM and gas adsorption.•Both VL and PL were considered when assessing the adsorption capacity of coals.•Coalification has ...significant effect on the fractal dimensions of coal samples.•D1 and D2 have different impacts on CH4 adsorption.
Coal is a porous medium with fractal characteristics. In order to investigate the effect of fractal dimensions on methane adsorption capacity, fractal characteristics of 11 coal samples were analyzed, using scanning electron microscopy (SEM) and low-pressure nitrogen gas adsorption (LP-N2GA). Data from SEM image analysis and LP-N2GA experiments were applied to assess the heterogeneities of pore distribution (D1) and the irregularities of coal surface (D2) on the basis of box-counting method and Frenkel–Halsey–Hill (FHH) theory, respectively. The relationship between fractal dimensions and coalification was investigated. Based on the physical description of fractal surfaces and pore distributions, the influence of fractal dimensions (both D1 and D2) on CH4 adsorption characteristics was also discussed. The results indicate that these coal samples have different CH4 adsorption characteristics and fractal geometries, with D1 ranging between 1.5380 and 1.8267, and D2 varying from 2.2656 to 2.6541. The U-shaped curve relationship between D values (including D1 and D2) and volatile matter (Vdaf) is observed, demonstrating that coalification makes coal surfaces and pore networks comparatively smoother and more regular for lower rank coals (Vdaf>15%), but rougher and more complex for higher rank coals (Vdaf<15%). The Langmuir volume (VL) shows a positive linear correlation with the fractal dimension D2 values, but little correlation with D1 values. While, the Langmuir pressure (PL) is affected by both D1 and D2. Fractal dimensions comprehensively reflect the difference in physical properties of coal, which can be used to evaluate CH4 adsorption capacity. Fractal analysis is of great significance for better understanding of the surface irregularity and methane storage capacity of a coal reservoir.
Lipoprotein(a) Lp(a) became besides LDL cholesterol one of the most attractive targets for intervention in cardiovascular disease. Strong genetic evidence supports the causal association between high ...Lp(a) concentrations and cardiovascular outcomes. Since specific Lp(a)-lowering therapies are under clinical investigation, the interest in measuring Lp(a) has markedly increased. However, the special structure of the lead protein component of Lp(a), named apolipoprotein(a), creates difficulties for an accurate measurement of Lp(a). A highly homologous repetitive structure, called kringle IV repeat with up to more the 40 repeats, causes a highly polymorphic protein. Antibodies raised against apolipoprotein(a) are mostly directed against the repetitive structure of this protein, which complicates the measurement of Lp(a) in molar terms. Both measurements in mass (mg/dL) and molar terms (nmol/L) are described and a conversion from one into the another unit is only approximately possible. Working groups for standardization of Lp(a) measurements are going to prepare widely available and improved reference materials, which will be a major step for the measurement of Lp(a). This review discusses many aspects of the difficulties in measuring Lp(a). It tries to distinguish between academic and practical concerns and warns to make a mountain out of a molehill, which does no longer allow to see the patient behind that mountain by simply staring at the laboratory issues. On the other hand, the calibration of some assays raises major concerns, which are anything else but a molehill. This should be kept in mind and we should start measuring Lp(a) with the aim of a better risk stratification for the patient and to identify those patients who might be in urgent need for a specific Lp(a)-lowering therapy as soon as it becomes available.
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•Measurement of Lp(a) in molar terms is desirable but not easy to accomplish.•The repetitive kringle IV repeat structure of apo(a) is the source of measurement problems of Lp(a).•The selection of the calibrators is of key importance and might improve the measurement performance of an Lp(a) assay.•Major efforts to better standardize Lp(a) measurements are under way and should be followed by assay manufacturers.•Despite the assays are not yet perfect, most of them can be used for risk stratification of the patients.
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