The phase behavior change when fluids are in a confined system has been an important issue after shale reservoirs became the focus of new oil and gas resources. Most studies on phase behavior of ...confined fluid systems have focused on modeling pore size dependence upon critical properties with no direct experimental evidence. Direct bubble point measurements of hydrocarbon mixtures in two synthesized mesoporous materials are provided in this work. Two different synthesized mesoporous silica materials, SBA-15 and SBA-16, having similar pore sizes (namely, 4 nm), were used. Well-ordered nanopores with narrow pore size distribution characterized these synthesized mesoporous silica materials. Decane–methane and octane–methane mixtures in 90:10 molar ratios were employed. The phase diagrams of the hydrocarbon mixtures were generated using a commercial thermodynamic simulator. The bubble point pressure of bulk (no porous medium) mixtures of decane–methane and octane–methane and the bubble point pressures with mesoporous materials (SBA-15 and SBA-16) were measured experimentally. Experiments were also performed with micrometer-sized sand particles. The bubble point pressure results of the hydrocarbon mixtures in the mesoporous materials were lower than those in the bulk, while the bubble points with sand were closer to those with bulk measurements. The bubble point pressure with SBA-15 having the higher total porosity and inner porosity was slightly lower than that with SBA-16. The differences may also be attributed to the different pore morphologies in the two mesoporous materials.
Conspectus Core principles of chemistry are ubiquitously invoked to shed light on the nature of molecular level interactions in nanoconfined fluids, which play a pivotal role in a wide range of ...processes in geochemistry, biology, and engineering. A detailed understanding of the physicochemical processes involved in the flow, structural transitions, and freezing or melting behavior of fluids confined within nanometer-sized pores of solid materials is thus of enormous importance for both basic research and technological applications. This Account provides a perspective on new insights into the thermodynamic and kinetic transitions of nanoconfined fluids in their stable and metastable forms. After briefly introducing the unique properties of mesoporous silicas from the SBA, MCM, and FDU families that serve as the confinement matrices, combining highly ordered single and bimodal mesopore architectures with tunable pore sizes in the ∼2–15 nm range and narrow size distributions, recent studies on melting/freezing behavior of water confined in these host matrices are reviewed. While differential scanning calorimetry (DSC) reveals a linear relationship between melting point depression and pore size (independent of the pore shape), as predicted by the Gibbs–Thomson relation, variable temperature 2H wide-line nuclear magnetic resonance (NMR) spectroscopy studies confirm the core–shell model of water and give evidence for a layer-by-layer freezing mechanism, which gives rise to an apparent fragile-to-strong transition in the solidification dynamics. In contrast to the freezing/melting behavior of water, the effect of nanoconfinement on the glass transition of supercooled liquids is nonuniversal and the glass transition temperature T g can either increase or decrease with the dimensionality and extent of confinement. This nonuniversal behavior is exemplified by the two glass-forming molecular liquids, glycerol and ortho-terphenyl (OTP). While glycerol shows an increase in T g and a pronounced slowdown of the rotational dynamics of the constituent molecules due to a change in the molecular packing between the bulk and the confined liquid, OTP displays a linear and confining-media-dependent depression of T g with increased confinement that is strongly influenced by the pore–liquid interface characteristics. This Account concludes with a focus on recent experimental evidence of extreme spatial and dynamical heterogeneity in both freezing and glass transition processes. This discovery was enabled by the unique mesoporous structures of SBA-16 and FDU-5, possessing bimodal architectures with two interconnected pore types of different size and shape (spherical and cylindrical). For the very first time, two melting points for water and two glass transitions for supercooled OTP, corresponding to a specific pore type, were observed. Collectively, these observations strongly suggest a close mechanistic connection between the local fluctuations in the structure and dynamics of nanoconfined liquids. While the findings reviewed in this Account provide new insights into thermodynamic and kinetic transitions of fluids, there remain many unanswered questions regarding the effects of nanoconfinement on the fundamental properties of fluids, which offer exciting future opportunities in chemical research.
Photonic crystal scales with a diamond‐based lattice from the weevil Lamprocyphus augustus are transformed into a high‐dielectric titania replica by a biotemplating double‐imprint route. ...Multidirectional optical reflectance spectroscopy of the replicated structure gives an angle‐independent reflection band in the visible spectrum, in agreement with photonic band structure calculations, which reveal the formation of a complete photonic bandgap at visible frequencies.
Immune-related alterations in Parkinson's disease (PD) can be monitored by assessing peripheral biological fluids that show that specific inflammatory pathways contribute to a chronic ...pro-inflammatory status. This pro-inflammatory activity is hypothesized to be already present in the prodromal stages of PD. These pathways maintain and reinforce chronic neurodegeneration by stimulating cell activation and proliferation what triggers the pro-inflammatory status as well. The gut microbiome possibly contributes to inflammatory pathways and shows specific differences in fecal samples from PD compared to healthy controls. In PD, Bacteroides abundance correlates with inflammatory markers in blood and motor impairment. Increased pro-inflammatory and decreased anti-inflammatory bacterial colonization can lead to changes in the metabolic pathways of amino acids, inducing increased membrane permeability, described as a leaky gut, enabling advanced contact between immune cells and gut microbiome and potentially a spreading of neuroinflammation through the body via the blood. Increased cytokine blood levels in PD are correlated with disease severity, motor symptoms, and clinical phenotypes.
α-synuclein is a central player in PD-associated inflammation, inducing specific T-cell activity and triggering microglial activation in the central nervous system (CNS). Misfolded α-synuclein propagation possibly results in the spreading of aggregated α-synuclein from neuron to neuron leading to a sustained neuroinflammation. This is supported by age-dependent defects of protein uptake in microglia and monocytes, so-called “inflammaging”, including α-synuclein oligomers, as the key pathological protein in PD.
Genetic risk markers and inherited forms of PD are also associated with inflammation, which is highly relevant for potential therapeutical targets.
The documented associations of inflammatory markers and clinical phenotypes indicate a pro-inflammatory concept of specific PD pathophysiology here. An in-depth understanding of inflammatory mechanisms in PD from bottom (gut) to top (CNS) and vice versa is needed to design novel immunomodulatory approaches to delay or even stop PD. Future studies focusing on structured protocols in large patient cohorts with appropriate control groups and comparative analysis among studies will aid the discovery of novel candidate biomarkers.
•Specific characteristics in PD gut microbiome induces metabolic changes and increased membrane permeability: “leaky gut”.•The "leaky gut" enables advanced contact between immune cells and gut microbiome.•Immune-related alterations in PD can be monitored in biological fluids from the periphery, already in prodromal stages.•α-synuclein induces specific T-cell activity, triggering microglial activation and possibly sustained neuroinflammation.•“inflammaging” in PD supports age-dependent defects in microglia and monocytes, including α-synuclein oligomer uptake.•Some genetic risk markers and inherited PD forms are associated with inflammation.
•Crack-free silica monoliths having only nano-sized pores were synthesized.•DSC thermograms of decane saturated in the monoliths showed two peaks.•TGA profiles of decane saturated in the monoliths ...showed early evaporation.•Bubble points of hydrocarbon mixtures in the monoliths were lower than in the bulk.
Silica based crack-free monoliths having the same pore size range as the oil and gas producing north-american shales were synthesized using a new synthesis procedure. Crack-free monoliths were synthesized by controlling the evaporation rate. Evaporation rate of 0.4 g/cm2 was found optimal for making monoliths in cylindrical enclosures of different sizes for experimentation. The focus of this work was to understand the effects of nano-sized porous media on the saturation pressures of a hydrocarbon mixture of methane and decane. The physicochemical properties of the synthesized monoliths were measured using X-ray diffraction (XRD), nitrogen adsorption/desorption isotherm (BET), pore size distribution curve, transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) of decane in saturated monoliths revealed different boiling points in comparison to pure decane. The experimentally measured saturation pressures at two different temperatures of the bulk hydrocarbon mixture (decane-methane) matched well with the simulated results. The bubble point pressures of a hydrocarbon mixture in the nano-sized monolith were lower (about 18%) than those in the bulk.
There is an urgent need to find reliable and accessible blood-based biomarkers for early diagnosis of Parkinson's disease (PD) correlating with clinical symptoms and displaying predictive potential ...to improve future clinical trials. This led us to a conduct large-scale proteomics approach using an advanced high-throughput proteomics technology to create a proteomic profile for PD. Over 1300 proteins were measured in serum samples from a de novo Parkinson's (DeNoPa) cohort made up of 85 deep clinically phenotyped drug-naïve de novo PD patients and 93 matched healthy controls (HC) with longitudinal clinical follow-up available of up to 8 years. The analysis identified 73 differentially expressed proteins (DEPs) of which 14 proteins were confirmed as stable potential diagnostic markers using machine learning tools. Among the DEPs identified, eight proteins—ALCAM, contactin 1, CD36, DUS3, NEGR1, Notch1, TrkB, and BTK— significantly correlated with longitudinal clinical scores including motor and non-motor symptom scores, cognitive function and depression scales, indicating potential predictive values for progression in PD among various phenotypes. Known functions of these proteins and their possible relation to the pathophysiology or symptomatology of PD were discussed and presented with a particular emphasis on the potential biological mechanisms involved, such as cell adhesion, axonal guidance and neuroinflammation, and T-cell activation. In conclusion, with the use of advance multiplex proteomic technology, a blood-based protein signature profile was identified from serum samples of a well-characterized PD cohort capable of potentially differentiating PD from HC and predicting clinical disease progression of related motor and non-motor PD symptoms. We thereby highlight the need to validate and further investigate these markers in future prospective cohorts and assess their possible PD-related mechanisms.
•Fourteen serum proteins were identified as stable potential diagnostic markers for PD.•Eight proteins correlated with longitudinal PD motor and non-motor scores.•Baseline serum α-synuclein levels correlated with two tyrosine kinases.•Proteins identified have functions in cell adhesion, axonal guidance or neuroinflammation.
Aim Several pathophysiological processes are involved in Parkinson's disease (PD) and could inform in vivo biomarkers. We assessed an established biomarker panel, validated in Alzheimer's Disease, in ...a PD cohort. Methods Longitudinal cerebrospinal fluid (CSF) samples from PPMI (252 PD, 115 healthy controls, HC) were analyzed at six timepoints (baseline, 6, 12, 24, 36, and 48 months follow-up) using Elecsys® electrochemiluminescence immunoassays to quantify neurofilament light chain (NfL), soluble TREM2 receptor (sTREM2), chitinase-3-like protein 1 (YKL40), glial fibrillary acidic protein (GFAP), interleukin-6 (IL-6), S100, and total alpha-synuclein (alphaSyn). Results alphaSyn was significantly lower in PD (mean 103 pg/ml vs. HC: 127 pg/ml, p0.05) and none showed a significant difference longitudinally. We found significantly higher levels of all these markers between PD patients who developed cognitive decline during follow-up, except for alphaSyn and IL-6. Conclusion Except for alphaSyn, the additional biomarkers did not differentiate PD and HC, and none showed longitudinal differences, but most markers predict cognitive decline in PD during follow-up.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To determine a general correlation between structure and dynamic magnetic properties of porous materials, the frequencies of magnetic spin waves are studied by Brillouin light scattering from nickel ...inverse opals and backed up by micromagnetic simulations. Within the observed unit cell size regime between 400 and 800 nm, discrete thickness standing modes are found to change with unit cell size. By applying pair correlation functions of the inverse opal solid phase normal to the applied field to an equation for perpendicular standing modes, the directional and unit cell size‐dependent spectral intensities above the surface mode region can be traced. Thus, an accessible general approach for the prediction of standing spin waves in porous materials is obtained.
General correlations between structure and standing spin wave mode frequencies in nickel inverse opals with varying unit cell sizes are determined by Brillouin light scattering and micromagnetic simulations. On this basis, an approach to trace the frequencies is developed, based on pair correlation functions of the inverse opal solid phase normal to the applied magnetic field.
Nanoconfined water plays a pivotal role in a vast number of fields ranging from biological and materials sciences to catalysis, nanofluidics and geochemistry. Here, we report the freezing and melting ...behavior of water (D
O) nanoconfined in architected silica-based matrices including Vycor glass and mesoporous silica SBA-15 and SBA-16 with pore diameters ranging between 4-15 nm, which are investigated using differential scanning calorimetry and
H nuclear magnetic resonance spectroscopy. The results provide compelling evidence that the extreme dynamical heterogeneity of water molecules is preserved over distances as small as a few angstroms. Solidification progresses in a layer-by-layer fashion with a coexistence of liquid-like and solid-like dynamical fraction at all temperatures during the transition process. The previously reported fragile-to-strong dynamic transition in nanoconfined water is argued to be a direct consequence of the layer-by-layer solidification.
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