Small Gas Molecules Research Articles

ReaxFF MD study on the early stage co-pyrolysis of mixed PE/PP/PS plastic waste

The early stage co-pyrolysis of typical plastic waste including polyethylene (PE), polypropylene (PP) and polystyrene (PS) were investigated by using the reactive force field molecular dynamics (ReaxFF MD) simulation with an automatic reaction mechanism analysis software (AutoRMA); the kinetic model, product yields and reaction process of co-pyrolysis were analyzed at atomic level. The results show that the kinetic parameters of PE/PP/PS co-pyrolysis can be obtained through the weighted sum of the parameters for the fracture of C–C and C–H bonds; the estimated activation energy is very close to the experimental one with a small error of ±3.86%, indicating that the fracture of C–C and C–H bonds can accurately characterize the co-pyrolysis process. For the co-pyrolysis of PE-PP mixture, an increase of PP content can improve the yields of oil and combustible gas, whereas for the co-pyrolysis of PP-PS mixture, the increase of PS content can improve the yields of tar and oil. In contrast, for the co-pyrolysis of PE-PP-PS mixture, a higher temperature is beneficial for the conversion of heavy oil into light oil; the light oil content increases from 44.77% at 2400 K to 56.18% at 3000 K. In addition, as a higher temperature can promote the further cracking of light hydrocarbons into gas products of smaller molecules, the yields of H2 and CH4 increase significantly with the increase of pyrolysis temperature, whereas the yields of C2H4 and C3H6 increase first and then decrease with the temperature. In comparison with the separated pyrolysis, the co-pyrolysis commences later, but displays shorter time to reach the first equilibrium state and generates products with smaller molecules. For the separate pyrolysis of PE and PP, their monomers emerge first, hereafter the alkanes and small molecule gases are produced; for the co-pyrolysis process, in contrast, the alkanes and small molecule gases are generated prior to the monomers. Moreover, PS tends to provide ·H radicals in the co-pyrolysis process, which can combine with the free radicals generated from PE and PP pyrolysis, forming small molecule alkanes and H2.

Influence of Metal Identity on Light-Induced Switchable Adsorption in Azobenzene-Based Metal-Organic Frameworks.

Energy-efficient capture and release of small gas molecules, particularly carbon dioxide (CO2) and methane (CH4), are of significant interest in academia and industry. Porous materials such as metal-organic frameworks (MOFs) have been extensively studied, as their ultrahigh porosities and tunability enable significant amounts of gas to be adsorbed while also allowing specific applications to be targeted. However, because of the microporous nature of MOFs, the gas adsorption performance is dominated by high uptake capacity at low pressures, limiting their application. Hence, methods involving stimuli-responsive materials, particularly light-induced switchable adsorption (LISA), offer a unique alternative to thermal methods. Here, we report the mechanism of a well-known LISA system, the azobenzene-based material PCN-250, for CO2 and CH4 adsorption. There is a noticeable difference in the LISA effect dependent on the metal cluster involved, with the most significant being PCN-250-Al, where the adsorption can change by 83.1% CH4 and 56.1% CO2 at 298 K and 1 bar and inducing volumetric storage changes of 36.2 and 33.9 cm3/cm3 at 298 K between 5 and 85 bar (CH4) and 2 and 9 bar (CO2), respectively. Using UV light in both single-crystal X-ray diffraction and gas adsorption testing, we show that upon photoirradiation, the framework undergoes a "localized heating" phenomenon comparable to an increase of 130 K for PCN-250-Fe and improves the working capacity. This process functions because of the constrained nature of the ligand, preventing the typical trans-to-cis isomerization observed in free azobenzene. In addition, we observed that the degree of localized heating is highly dependent on the metal cluster involved, with the series of isostructural PCN-250 systems showing variable performance based upon the degree of interaction between the ligand and the metal center.

Metallocavitins as Promising Industrial Catalysts: Recent Advances.

The energy, material, and environmental problems of society require clean materials and impose an urgent need to develop effective chemical processes for obtaining and converting energy to ensure further sustainable development. To solve these challenges, it is necessary, first of all, to learn solar energy harvesting through the development of artificial photosynthesis. In our planet, water, carbon dioxide, and methane are such affordable and inexhaustible clean materials. Electro/photocatalytic water splitting, and also CO2 and CH4 transforming into valuable products, requires the search for relevant efficient and selective processes and catalysts. Of great interest is the emerging new generation of bioinspired catalysts—metallocavitins (MCs). MCs are attracting increasing attention of researchers as advanced models of metalloenzymes, whose efficiency and selectivity are well known. The primary field of MC application is fine organic synthesis and enantioselective catalysis. On the other hand, MCs demonstrate high activity for energy challenging reactions involving small gas molecules and high selectivity for converting them into valuable products. This mini-review will highlight some recent advances in the synthesis of organic substances using MCs, but its main focus will be on the rapid development of advanced catalysts for the activation of small molecules, such as H2O, CO2, and CH4, and the prospects for creating related technological processes in the future.

Theoretical Study of Small Molecules Adsorption on Pristine and Transition Metal Doped GeSe Monolayer for Gas Sensing Application.

By using first-principles calculations, the sensing properties of pristine and transition metal (TM) atoms (Ti, V, and Co) embedded germanium selenide (GeSe) monolayer toward small gas molecules (H2, NH3, CO, O2, SO2, NO, and NO2) were investigated. The adsorption energies, electronic structure, optical properties, and recovery time of the adsorption systems were calculated and analyzed in detail. The results indicate that TM doped GeSe has stronger interaction with gas molecules compared with the pristine GeSe monolayer. Especially for Ti- and V-GeSe monolayer, the absolute value of adsorption energies are up to 2 eV for O2, NO, and NO2. The doping with TM atoms also changes the charge transfer and electronic structures of adsorption systems. Combined with the result of the calculated optical properties and recovery time, it can be concluded that Ti-GeSe monolayer has great potential for NH3 detection, while Co-GeSe monolayer can be very promising SO2 gas sensors.

Exploring tuning phenomena of THF-H2 hydrates via molecular dynamics simulations

The tuning phenomenon is one of the effective strategies to enhance the gas storage density of clathrate hydrates at moderate pressure: small gaseous guest molecules can occupy some of the large cages of binary hydrates that are not occupied by thermodynamic promoters. This work explored tuning phenomena in THF-H2 hydrates at the molecular level by all-atomic molecular dynamics simulations for the first time. Before conducting molecular dynamics simulations, off-diagonal Lennard-Jones (LJ) parameters between the center of mass of H2 and oxygen of H2O were optimized from ab-initio calculations with various configurations of H2 and H2O molecules. These optimized off-diagonal parameters provided reasonable phase equilibrium of THF-H2 hydrates compared to the simple mixing rule case, which is derived from weakened H2-H2O interaction and active drifting of H2 in molecules’ 512 cages. With the ab-initio modified LJ parameters, the growth of THF-H2 hydrates was investigated by molecular dynamics simulations under various compositions and pressures of the system. Cage occupancy of H2 in 512 cages of the binary hydrates increased when the THF concentration was lower than 5.56 mol%, but double occupation of H2 in 512 cages was not observed. Cage occupancy of H2 in 51264 cages significantly increased by lowering the THF concentration, and the total storage capacity of H2 increased by multiple occupations of H2 in the 51264 cages. The growth rate of the THF-H2 hydrates depended on the THF concentration, and that dependency of the growth rate was due to the wrong adsorption of THF molecules at open small cage sites of the solution-hydrate interface. These results demonstrated that uptake of H2 could be enhanced by the tuning phenomena when mobile THF molecules in the liquid phase formed binary hydrates with H2.

Recent advances in inhibiting atherosclerosis and restenosis: from pathogenic factors, therapeutic molecules to nano-delivery strategies.

Due to dominant atherosclerosis etiology, cardiovascular diseases (CVDs) remain the leading cause of morbidity and mortality worldwide. In clinical trials, advanced atherosclerotic plaques can be removed by angioplasty and vascular transplantation, but the severe risk of vascular restenosis remains, which needs to be urgently improved. After understanding and generalizing the pathological processes and cellular mechanism of certain atherosclerosis and restenosis, their essential pathogenic factors show noteworthy similarity, primarily including endothelium injury, excessive proliferation of smooth muscle cells (SMCs), and pathogenic inflammatory responses. These common pathogenic factors inspire researchers to develop co-target treatments for these atherosclerosis and restenosis. Numerous therapeutic agents such as nucleic acids, proteins, small molecule drugs and gas signaling molecules for co-target treatments are summarized in this paper. To improve the safety and effectiveness of therapeutic agents, high-performance nanodelivery strategies have been developed for anti-atherosclerosis via systemic administration and anti-restenosis via local administration. They can augment blood circulation time and targeting ability for systemic administration, as well as efficient nanodrug load and precise release. Overall, this review aims to recapitulate the emerging therapeutic molecules and nanodelivery strategies for the treatment of atherosclerosis and restenosis, with the goal of mutual enlightenment in exploring therapeutic approaches for these diseases.

Fluorinated tris(pyridyl)borate ligand support on coinage metals.

A useful ligand involving three pyridyl donor arms and fluorocarbon substituents surrounding the coordination pocket has been assembled and utilized in coinage metal chemistry. This tris(pyridyl)borate serves as an excellent ligand support for the stabilization of ethylene complexes of copper, silver and gold.

Ab-initio modelling for gas sensor device: based on Y-doped SnS2 monolayer

In this work, we have investigated the adsorption behavior of small gas molecules like CO, NO, CO 2 , NO 2 and NH 3 on Yttrium(Y) doped SnS 2 monolayer by employing density functional theory simulations. Y-doping effect on the physicochemical properties of the pure SnS 2 monolayer is first studied, then adsorption mechanism was analyzed by adsorption energy, charge transfer, structural properties, magnetic properties , electronic properties such as density of states, charge density and band structure. In addition, the transport properties are evaluated to propound the gas adsorption response of Yttrium (Y) doped -SnS 2 system on the device level. The result shows that all the gas molecules were strongly adsorbed on the Yttrium (Y) site of the Y-doped SnS 2 monolayer through formation of strong covalent bonds and Y- doped SnS 2 monolayers can be employed as a potential candidate for gas sensing applications. Here in, to evaluate the sensing capability, the molecular model of the adsorption systems was constructed, and density functional theory (DFT) was used to calculate the adsorption behavior of these gases. • Yttrium(Y) doped SnS 2 monolayer was investigated as gas sensor. using DFT calculation. • Doping of Y atom modulates the electronic behavior of SnS 2 monolayer from semi-conductor (1.64 eV) to metal. • The gas adsorption energy of all gases are in trend with the interaction distance and charge transfer. • Transport properties are evaluated for device level modeling of Y-doped SnS 2 system.

Simulation of Gas Production Mechanisms in Shear Deformation of Medium-Rank Coal.

The discovery of mechanochemical action provides a theoretical basis for revealing gas production from coal under stress degradation. The research on gas production in such a manner is conducive to revealing mechanisms of coal and gas outburst and excess coalbed methane (CBM). By selecting a model of a macromolecular structure of Given medium-rank coal, its structure was optimized based on molecular mechanics, molecular dynamics, and quantum chemistry, and the six optimized models were constructed into a coal polymer cell. The coal polymer cell was loaded to shear deformation through large-scale atomic/molecular massively parallel simulator (LAMMPS) software. The Given model was optimized by quantum chemistry software Gaussian and the frequency was calculated to obtain the bond strength and average local ionization energy (ALIE). The following understanding was reached: under shear, bridge bonds of a ring structure, and large π-bonds are subjected to shear and tensile action, and atoms (atomic clusters) in the outermost region of coal macromolecules tend to be sheared by surrounding molecules. The shear action shortens a molecular chain of medium-rank coal with a cross-linked structure and promotes the evolution of the coal macromolecular structure. The shear action can lead to the formation of free radicals, such as H• and •CO from macromolecules of medium-rank coal, thus producing many small gas molecules, such as H2 and CO. Moreover, the shear action can not only break chemical bonds but also can produce new chemical bonds. The research on gas production mechanisms under shear deformation of medium-rank coal provides a certain reference for studying mechanochemistry.

Adsorption of gas molecule on Rh, Ru doped monolayer MoS2 for gas sensing applications: A DFT study

In this paper, the interactions of small gas molecules (CO2, H2O and SO2) with pure MoS2, Rh-MoS2 and Ru-MoS2 were investigated through using of DFT calculations to explore their potential applications as gas sensing. The SO2 gas molecule was found to interact most strongly with the monolayer Ru doped MoS2 with a higher adsorption energy of 1.87 eV. Besides, the SO2 gas molecule were chemisorption on the monolayer surface due to the strong interaction between monolayer Ru-MoS2. Most notably, the monolayer Ru-MoS2 might be a great candidate for efficient SO2 gas sensor.

Mechanism analysis of gas products from catalytic pyrolysis of tire rubber based on reaction thermodynamics and kinetics

In this paper, the gas products from pyrolysis of tire rubber was respectively studied by fixed bed pyrolysis experiments—gas chromatography analysis and molecular dynamics simulations. The results of experiments showed that the main gas products of pyrolysis were CH4, H2, and C2H4. The simulation results showed that the long rubber chain broke into four main rubber monomers at low temperature: isoprene, styrene, 1,3-butadiene and uncondensated C4H6·. And at higher temperature, the generated monomers were pyrolyzed into small molecule gases. Fe2O3 reduced the final pyrolysis temperature and increased the pyrolysis rate with a good catalytic reactively. And it changed the gas products distribution, in which the proportion of CH4 and H2 were promoted while the proportion of C2H4 was reduced. In order to obtain the thermodynamic and kinetic data of each reaction path, DFT calculation was carried out. The reaction paths of three major radicals H·, CH3·, and CH2 = CH· were further discussed. The results showed that Fe2O3(commercial) promoted the release of CH3· from isoprene monomer and CH3· attack on isoprene monomer and 1,3-butadiene to produce CH4. Moreover, Fe2O3 promoted H· attacking styrene monomer to generate H2.

Procognitive activity of nitric oxide inhibitors and donors in animal models

Nitric oxide is a small gaseous molecule that plays important roles in the majority of biological functions. Impairments of NO-related pathways contribute to the majority of neurological disorders, such as Alzheimer's disease (AD), and mental disorders, such as schizophrenia. Cognitive decline is one of the most serious impairments accompanying both AD and schizophrenia.In the present study, the activities of NO donors, slow (spermine NONOate) or fast (DETANONOate) releasers, and selective inhibitor of neuronal nitric oxide synthase N(ω)-propyl-l-arginine (NPLA) were investigated in pharmacological models of schizophrenia and AD. Cognitive impairments were induced by administration of MK-801 or scopolamine and were measured in novel object recognition (NOR) and Y-maze tests. The compounds were investigated at doses of 0.05–0.5 mg/kg. The dose-dependent effectiveness of all the compounds was observed in the NOR test, while only the highest doses of spermine NONOate and NPLA were active in the Y-maze test. DETANONOate was not active in the Y-maze test. The impact of the investigated compounds on motor coordination was tested at doses of 0.5 and 1 mg/kg. Only NPLA at a dose of 1 mg/kg slightly disturbed motor coordination in animals.

Hydrate growth kinetics in marine sediments

Clathrate hydrates form and grow when small gas molecules (<0.9 nm) come to contact with water at favorable pressure and temperature conditions. It happens in both the interstitial pore space between distributed marine sediments and inside their nano-meter sized pore spaces. For several thousands of years, the hydrates have occurred abundantly in permafrost and under the sea floor locking an immense amount of energy in the form of natural gas. It is estimated that the total gas reserved in hydrate deposits can meet our primary energy demand for a couple of centuries. To understand their formation and subsequent growth, several formulations have been derived at fundamental level. Various simplified assumptions still make those models really complicated and lead to provide reasonably large errors in prediction. Unfortunately, there is no direct correlation available so far that can precisely predict the hydrate kinetics with most simple way. This work introduces the development of a non-fundamental model routed through the concept of clathrate physics. To investigate the versatility and effectiveness of this growth model, it is used to predict the real-time data comparing with existing physical models.

Gas velocimetry based on infrared laser-induced fluorescence

A novel method for gas velocity field measurements by means of infrared molecular tagging velocimetry is reported with proof-of-principle demonstration in a carbon dioxide (CO2) axisymmetric turbulent jet. Infrared laser-induced fluorescence utilizes the resonant vibrational energy level transitions of small gas molecules, such as CO2, to “tag” and trace the flow of the molecules by taking subsequent images of the infrared emission. Spectroscopic model of the molecular vibrational energy transfer processes is taken into account to design and optimize the measurement scheme. The infrared images are then analyzed, with detailed consideration of molecular diffusion, lateral velocity, and fluorescence lifetime, to yield quantitative velocity field distribution. The radial velocity distributions in the jet main region, with velocities ranging from 7 to 50 m/s, are obtained and shown to be in excellent agreement with theoretical predication and previous experimental works. Velocity uncertainties are discussed and estimated to be 7.7%, 6.7%, 6.1% for Re = 104, 2×104, 3×104 (maximum velocity uc=18.3,34.6,50.5 m/s), respectively. Spatial resolution along the laser beam is estimated to be 107 μm. To the best of the authors' knowledge, this is the first work of infrared molecular tagging velocimetry. With powerful excitation lasers targeting strong infrared molecular absorption transitions, this technique presents great potential for simultaneous flow-scalar field measurements at much-improved accuracy, spatial and temporal resolution, that can be used for the study of low-speed micro-flows, or instantaneous snapshots of turbulent flows.

Gas molecules (CH4, CO, H2O and H2S) adsorption on VC (001)surface: a first principles study

The first principle plane wave pseudo-potential method based on density functional theory system is used to calculate and simulate the geometric structure, density of states and optical properties of intrinsic VC materials. And we further studied the adsorption performance of small gas molecules (CH4, CO, H2O, H2S) on the surface of VC(001). The most stable adsorption geometry of CH4, CO, H2O and H2S on the intrinsic VC(001) was determined, and the electronic structure and differential charge were calculated by the first principle method. The results show that the adsorption stability of the same molecule on the surface is related to the interaction position between the molecule and the surface after adsorption. According to the analysis of the differential charge density and the charge layout number, the charge layout number of the central atom C, O, S of the gas molecule increases after adsorption, and the adsorption strength of the gas molecule on the surface is CO > H2S > H2O > CH4. The H2S adsorbed on VC surface has the strongest adsorption energy (–1.442 eV) and more transfer charge (–0.12 e). The calculated dielectric function results shows that the existence of gases molecules inhibited the photon adsorbed on VC(001) surface. Our research provide a theoretical basis for further research on the gas sensing properties of material.

Inorganic gas sensing performance of χ3-borophene and the van der Waals heterostructure

Recently, two-dimensional (2D) material χ3-borophene has been synthesized in experiment. Combining density functional theory with non-equilibrium Green's function method, in the present work we theoretically investigated the adsorption behaviors of small gas molecules NO, NO2, NH3, CO and CO2 on χ3-borophene, and corresponding transport properties and sensing performance. Our results suggest that NO, NO2, NH3 and CO adsorb on this 2D material by chemical adsorption, while CO2 adopts physical adsorption. The transport properties of χ3-borophene are sensitive to the adsorption of NO, NO2, NH3 and CO, thus it can be used to construct gas sensor for these gas molecules. Especially, χ3-borophene is very sensitive to NO and, more interestingly, the sensing performance for NO can be greatly improved by applying in-plane strain. In addition, using semiconductor WSe2 as the substrate, we theoretically predicted a kind of van der Waals heterostructure. It is found that, although the adsorption behaviors of NO, NO2, NH3 and CO on χ3-borophene are hardly affected by the substrate, WSe2 can effectively enhance the stability of χ3-borophene and positively modulate the sensing performance, suggesting an actual way to realize χ3-borophene gas sensor.

Low-cost and facile fabrication of defect-free water permeable membrane for CO2 hydrogenation to methanol

CO2 hydrogenation to methanol is a high value-added way for CO2 utilization. However, the conversion of CO2 to methanol is severely limited by the thermodynamic equilibrium. Using water permeable membranes to simultaneously remove the by-product (H2O) during the reaction can overcome this limitation, and enhance CO2 conversion and methanol yield. In this work, a defect-free NaA zeolite membrane supported on an alumina hollow fiber substrate was fabricated via a totally template-free method with the capability to scale up at a low cost in the future. Furthermore, the as-synthesized membrane can effectively separate water from other small gas molecules (H2 and CO2) under extremely harsh conditions (T ≥ 200℃ and P ≥ 20 bar), with a water flux up to 4.8 × 10-7 mol m−2 s−1 Pa−2 and superior separation factor for H2O/H2 (>10000), H2O/CO2 (>10000) and H2O/CH3OH (>300). With this remarkable separation performance, this zeolite membrane is promising to be applied in CO2 hydrogenation to methanol. Moreover, DFT analysis provides more insights to explain the water separation behavior of this membrane.

Enhanced Breaking of Lignin and Mesopore Formation in Zinc Chloride Assisted Hydrothermal Carbonization of Waste Biomasses

Hydrochars from hydrothermal carbonization of different biowaste materials (dried dandelion, sawdust, coconut shell powder) formed in the presence of aqueous salt solutions were compared to those obtained by the common method in pure water. Hydrochars with increased carbon contents, pore volume and surface areas were specifically obtained from coconut shell powder in the presence of zinc chloride. Compositional and structural changes within the hydrochar products caused by the process conditions and/or the additive were characterized by solid state 13C NMR spectroscopy, proving that cellulose and, in particular, lignin units in the biomass are more easily attacked in the presence of the salt. Under saline conditions, a distinct particle break-up led to the creation of mesoporosity, as observable from hysteresis loops in nitrogen adsorption isotherms, which were indicative of the presence of pores with diameters of about 3 to 10 nm. The obtained hydrochars were still rich in functional groups which, together with the mesoporosity, indicates the compounds have a high potential for pollutant removal. This was documented by adsorption capacities for the methylene blue and methyl orange dyes, which exceeded the values obtained for other hydrochar-based adsorbers. A subsequent physical activation of the mesoporous hydrochars in steam at different temperatures and times resulted in a further drastic increase in the surface areas, of up to about 750 m2/g; however, this increase is mainly due to micropore formation coupled with a loss of surface functionality. Consequently, the adsorption capacity for the quite large dyes does not provide any further benefit, but the uptake of smaller gas molecules is favored.

The Synthesis and Properties of TIPA-Dominated Porous Metal-Organic Frameworks.

Metal-Organic Frameworks (MOFs) as a class of crystalline materials are constructed using metal nodes and organic spacers. Polydentate N-donor ligands play a mainstay-type role in the construction of metal−organic frameworks, especially cationic MOFs. Highly stable cationic MOFs with high porosity and open channels exhibit distinct advantages, they can act as a powerful ion exchange platform for the capture of toxic heavy-metal oxoanions through a Single-Crystal to Single-Crystal (SC-SC) pattern. Porous luminescent MOFs can act as nano-sized containers to encapsulate guest emitters and construct multi-emitter materials for chemical sensing. This feature article reviews the synthesis and application of porous Metal-Organic Frameworks based on tridentate ligand tris (4-(1H-imidazol-1-yl) phenyl) amine (TIPA) and focuses on design strategies for the synthesis of TIPA-dominated Metal-Organic Frameworks with high porosity and stability. The design strategies are integrated into four types: small organic molecule as auxiliaries, inorganic oxyanion as auxiliaries, small organic molecule as secondary linkers, and metal clusters as nodes. The applications of ratiometric sensing, the adsorption of oxyanions contaminants from water, and small molecule gas storage are summarized. We hope to provide experience and inspiration in the design and construction of highly porous MOFs base on polydentate N-donor ligands.

A Nitric Oxide–Modulated Variable-Order Fractional Maxwell Viscoelastic Model of Cerebral Vascular Walls

It is well known that the mechanical behavior of arterial walls plays an important role in the pathogenesis of vascular diseases. Most studies existing in the literature focus on the mechanical interactions between the blood flow and wall’s deformations. However, in the brain, the smaller vessels experience not only oscillatory forces due to the pulsatile blood flow but also structural and morphological changes controlled by the surrounding brain cells. In this study, the mechanical deformation of the cerebral arterial wall caused by the pulsatile blood flow and the dynamics of the neuronal nitric oxide (NO) is investigated. NO is a small diffusive gaseous molecule produced by the endothelial cells and neurons, which is involved in the regulation of cerebral blood flow and pressure. The cerebral vessel is assumed to be a hollow axial symmetric cylinder whose wall thickness is much smaller than the cylinder’s radius and longitudinal length is much less than the propagating wavelength. The wall is an isotropic, homogeneous linear viscoelastic material described by an NO-modulated variable-order fractional Maxwell model. A fractional telegraph equation is obtained for the axial component of the displacement. Patterns of wall’s deformation are investigated through numerical simulations. The results suggest that a significantly decreased inactivation of the neuronal NO may cause a reduction in the shear stress at the blood-vessel interface, which could lead to a decrease in the production of shear-induced endothelial NO and neurovascular disease.