C1 Values Research Articles

Anchura del bulbo de la arteria carótida interna: un nuevo parámetro potencial para la predicción de enfermedades vasculares cerebrales

ObjectiveTo investigate the relationship between the width of the internal carotid artery (ICA) bulb and cerebral vascular diseases including stroke and intracranial aneurysms. Material and methodsIn total 300 patients who had supra-aortic computed tomography angiography (CTA) were enrolled in this study from 2015 to 2021. The study groups consisted of 100 ischemic stroke patients, 100 patients with intracranial aneurysms, and 100 control subjects. The intracranial aneurysm patient group was divided into two subgroups according to the presence of subarachnoid hemorrhage (SAH). The largest diameters of the ICA C1 (cervical) and C2 (petrous) segments in all individuals were measured bilaterally on CTA images. The ICA diameter ratios of the cases were measured using the formula (C1-C2)/C1. The relationship between the age and ICA vessel analysis was evaluated as well. ResultsThe mean ICA bulb width values in the ischemic stroke patient group and the intracranial aneurysm patient group were significantly higher than the control group (P<.001). The ICA C1 and C2 segment diameter values and ICA diameter ratio were smaller in the intracranial aneurysm patients with SAH than those who had not (P= 0.7). There was a statistically significant but weak relationship between the age and ICA diameter ratios in all study groups (R-squared value of 0.26, P= 0.03). ConclusionICA bulb width is a parameter that can be easily evaluated with neuroimaging modalities and is a successful method that may be used for predicting the risk of ischemic stroke or the presence of an intracranial aneurysm.

Origin and microbial degradation of thermogenic hydrocarbons within the sandy gas hydrate reservoirs in the Qiongdongnan Basin, northern South China Sea

Large-scale natural gas hydrate accumulations (generally over one billion cubic meters of natural gas) in coarse-grained marine sediments are the most valuable types for commercial exploration and exploitation. The formation of such a gas hydrate deposit generally requires a sufficient natural gas supply such as deeply buried thermogenic gas source. However, the worldwide discovered thermogenic gas hydrate deposits are rare, leaving relatively a poor understanding of their formation and evolution. Based on the geochemical and microbial analyses of eleven hydrate-related gas and five sediment samples from the thermogenic gas hydrate deposits in the Qiongdongnan Basin in northern South China Sea, we systematically investigated the origin and evolution of thermogenic hydrocarbons within sandy gas hydrate reservoirs. Results show that natural gas within high saturated gas hydrate-filled sandy sediments is predominately of thermogenic (the proportion is 57.1–70.5%), characterized by “dry gas” (99.38–99.7% C1, 0.26–0.47% C2 and <0.5% C3+), relatively lower C1/(C2+C3) ratio (187–376), and heavier δ13C–C1 values (−55.0 to −31.3‰). In addition, typical biomarkers (including the alkanes, tricyclic terpanes, hopanes and steranes) generated from mature source rocks were detected in the hydrate-filled fine sand reservoir, as well as the biomarker indicators (including the unresolved complex mixtures (UCMs) hump and the 25-norhopane homologous series) for severe hydrocarbon biodegradation. Furthermore, large amounts of hydrocarbon degrading bacteria (50.5% of bacteria) and methanogenic archaea (34.3% of archaea) were detected within hydrate-filled sandy sediment. Our results indicated that the deeply buried thermogenic source can indeed provide sufficient gas supply for the formation of a large-scale gas hydrate deposit, but thermogenic liquid hydrocarbons within gas hydrate reservoirs are very susceptible to be degraded and consumed by hydrocarbon degrading bacteria. In addition, we also found that the clay components of argillaceous gas hydrate reservoirs can adsorb and store large amounts of in situ immature organic matter, which can significantly obscure or cover up the original geochemical signatures of thermogenic hydrocarbons therein. These findings suggest that the relative contribution of deeply buried thermogenic source for gas hydrate accumulation worldwide may be underestimated, because we have previously ignored the fact that thermogenic hydrocarbons within gas hydrate reservoirs would be significantly consumed by hydrocarbon degrading microbes or diluted by in situ immature sedimentary organic matter. Our findings are highly significant for the evaluation and exploration of thermogenic gas hydrate accumulations worldwide.

Internal carotid artery bulb width: a novel potential parameter for the prediction of cerebral vascular diseases

ObjectiveTo investigate the relationship between the width of the internal carotid artery (ICA) bulb and cerebral vascular diseases including stroke and intracranial aneurysms. Material and methodsIn total 300 patients who had supra-aortic computed tomography angiography (CTA) were enrolled in this study from 2015 to 2021. The study groups consisted of 100 ischemic stroke patients, 100 patients with intracranial aneurysms, and 100 control subjects. The intracranial aneurysm patient group was divided into two subgroups according to the presence of subarachnoid hemorrhage (SAH). The largest diameters of the ICA C1 (cervical) and C2 (petrous) segments in all individuals were measured bilaterally on CTA images. The ICA diameter ratios of the cases were measured using the formula C1-C2C1. The relationship between the age and ICA vessel analysis was evaluated as well. ResultsThe mean ICA bulb width values in the ischemic stroke patient group and the intracranial aneurysm patient group were significantly higher than the control group (p < 0.001). The ICA C1 and C2 segment diameter values and ICA diameter ratio were smaller in the intracranial aneurysm patients with SAH than those who had not (p = 0.7). There was a statistically significant but weak relationship between the age and ICA diameter ratios in all study groups (R-squared value of 0.26, p = 0.03). ConclusionICA bulb width is a parameter that can be easily evaluated with neuroimaging modalities and is a successful method that may be used for predicting the risk of ischemic stroke or the presence of an intracranial aneurysm.

Corrosion resistance of structural metals depending on the sample orientation and initial exposure conditions in coastal and rural atmospheres. Part 1. Corrosivity toward structural metals at coastal and rural test sites under various exposure conditions

ABSTRACT Four 1-year tests of metal samples (carbon steel, zinc, copper, aluminum, and D16 alloy) were carried out at locations with coastal and rural atmospheres to determine corrosion losses and the rate of chloride deposition ([Cl-]) on the upper and lower sample sides. [Cl-] were determined for different orientations relative to the sea winds on coastal sites. A methodology for testing metal samples is presented and the values of the first-year corrosion losses of metals (C1) are reported. It is shown that the corrosion of metals is significantly affected by the season of when the samples are installed. The atmosphere corrosivity under each conditions of sample exposure is estimated by the C1 values calculated using the developed dose-response functions (DRFs). It has been shown that the DRFs can be used to predict C1 and estimate the atmosphere corrosivity categories at locations with various types of atmosphere and under various exposure conditions.

Electrocoalescence Behavior of Droplets Dispersed with Na2CO3 in Oil under the Electromagnetic Synergy Field.

Electromagnetic synergy is a more effective physical method than a single AC electric field (ACEF) to enhance oil-water separation. However, the electrocoalescence behavior of droplets dispersed with salt ions in oil under the synergistic electromagnetic field (EMSF) still lacks research. Herein, the evolution coefficient of liquid bridge diameter (C1) characterizes the growth rate of the liquid bridge diameter, a series of Na2CO3-dispersed droplets with different ionic strengths were prepared, and C1 values of droplets under ACEF and EMSF were compared. Micro high-speed experiments revealed that C1 under ACEF is larger than C1 under EMSF. In particular, when σ = 100 μS·cm-1and E = 629.73 kV·m-1, C1 under the ACEF is 15% larger than C1 under EMSF. Additionally, the theory of ion enrichment is put forward, which explains the influence of salt ions on ζ potential and total surface potential in EMSF. This study provides guidance for designing high-performance devices by introducing electromagnetic synergy in water-in-oil emulsion treatment.

Surface Morphology, Compressive Behavior, and Energy Absorption of Graded Triply Periodic Minimal Surface 316L Steel Cellular Structures Fabricated by Laser Powder Bed Fusion

Laser powder bed fusion (LPBF) is an emerging technique for the fabrication of triply periodic minimal surface (TPMS) structures in metals. In this work, different TPMS structures such as Diamond, Gyroid, Primitive, Neovius, and Fisher-Koch S with graded relative densities are fabricated from 316L steel using LPBF. The graded TPMS samples are subjected to sandblasting to improve the surface finish before mechanical testing. Quasi-static compression tests are performed to study the deformation behavior and energy absorption capacity of TPMS structures. The results reveal superior stiffness and energy absorption capabilities for the graded TPMS samples compared to the uniform TPMS structures. The Fisher-Koch S and Primitive samples show higher strength whereas the Fisher-Koch S and Neovius samples exhibit higher elastic modulus. The Neovius type structure shows the highest energy absorption up to 50% strain among all the TPMS structures. The Gibson-Ashby coefficients are calculated for the TPMS structures, and it is found that the C2 values are in the range suggested by Gibson and Ashby while C1 values differ from the proposed range.

State of charge estimation of ultracapacitor based on forgetting factor recursive least square and extended Kalman filter algorithm at full temperature range

State of charge (SOC) of ultracapacitor plays an important role in the energy management optimization of hybrid energy storage system for electric vehicles. In addition to the perfection of the model and the SOC estimation algorithm, the parameter identification method and temperature factor should also be considered. In this paper, an ultracapacitor test platform is established, the characteristic parameters of ultracapacitor at full temperature range are obtained. This paper uses the forgetting factor recursive least squares algorithm (FFRLS) to identify the parameters of the second-order equivalent circuit model of ultracapacitor online. The extended Kalman filter (EKF) algorithm is used to estimate the SOC of ultracapacitor cell. The results show that: (1) FFRLS algorithm can identify R0, R1, R2, C1, and C2 values of ultracapacitor at full temperature range. Under the hybrid pulse power characterization working condition, the average mean absolute error between the estimated voltage and the actual voltage is about 0.0132 V. (2) EKF algorithm has a good adaptability to estimate SOC of ultracapacitor under different temperatures and working conditions. The SOC estimation error under different working conditions is low. From the perspective of mean square error, the estimation error at −20°C is the lowest. (3) FFRLS and EKF joint estimation algorithm with good robustness and reliability can be used to estimate the SOC of ultracapacitor under different temperatures and working conditions. This study can provide a useful guidance for the parameter identification and SOC estimation of ultracapacitor for electric vehicle at different temperatures.

Spatio-temporal variation of Dissolved Organic Matter (DOM) in the Bohai Sea and the Yellow Sea

The seasonal and spatial variations of dissolved organic carbon (DOC), chromophoric dissolved organic matter (CDOM), and fluorescent dissolved organic matter (FDOM) were evaluated in the Bohai Sea (BS) and the Yellow Sea (YS) during three cruises. Two fluorescence components, such as marine humic-like (C1) and visible humic-like (C2), were identified using excitation-emission matrix fluorescence spectroscopy (EEMs) and parallel factor analysis (PARAFAC). The average values of DOC concentration, CDOM absorption coefficient (aCDOM(355)) and fluorescence component intensities (C1 and C2) were significantly higher in the BS (2.14 mg C L−1, 0.77 m−1, 0.035 RU, 0.026 RU, respectively) than those in the YS (1.55 mg C L−1, 0.50 m−1, 0.025 RU, 0.019 RU, respectively). The average DOC value was highest in winter (2.16 mg C L−1) and lowest in spring (1.62 mg C L−1), while aCDOM(355) was the opposite (winter: 0.45 m−1; spring: 0.62 m−1; summer: 0.58 m−1). The average C1 (0.042 RU) and C2 (0.028 RU) values were highest during the winter and summer respectively, and lowest during spring (C1: 0.024 RU; C2: 0.016 RU). DOC and CDOM were mainly derived from terrestrial input, during the winter and spring, while they were primarily derived from phytoplankton production during the summer. C1 and C2 were not correlated with salinity or chlorophyll a during the three seasons. The SUVA355 values generally decreased with increasing salinity during the spring and summer, indicating that sources and sinks of CDOM and DOC were uncoupled. DOC, CDOM, and FDOM were dominated by terrestrial input and phytoplankton production activities and their spatial distributions and seasonal variations were also affected by currents, microbial activities, and photobleaching.

Determination of Rheological Properties of Alternative Flour Substituted Doughs

All over the world, healthy foods, functional foods, diet foods and many similar terms are on the agenda. Consumers are offered different types of foods for a healthy diet. To this end, studies to improve the functional properties of bread have gained momentum. One of the ways to improve the functional properties of bread is to use flours with more functional properties than wheat flour. However, the effects of the added flours on the rheology of the dough are also different. The aim of this study is to determine the effects of flours (buckwheat (10-30%), carob (3, 6, 9, and 12), chickpea (10-50%), oat (10-50%), and barley (10-50%)) in different proportions added to bread flour on the rheological properties of the dough. The Mixolab® (Chopin) instrument was used to determine the rheological properties. A standard protocol for flour analysis was used for the analysis of bread flour and other flour mixtures. Various rheological and other dough properties were determined, such as water holding capacity, development time, stability, amylase activity, and degree of flour retrogradation. Using the obtained Mixolab® curve, C1 values for water retention and stability, C2 values for protein quality, C3 values for starch gelatinization, C4 values for amylase activity, and C5 values for degree of starch degradation were measured. C1 changed between 1.05 and 1.16 Nm, C2 between 0.33 and 0.58 Nm, C3 between 1.22 and 2.13 Nm, C4 between 0.96 and 1.98 Nm, and C5 between 0.95 and 2.81 Nm depending on the flour ratio and type used. As a result of the tests, it was determined that the most suitable flour for bread flour profile is 30% barley flour, 20% oat flour, 9% carob flour and 20% buckwheat flour, separately for each added flour.

Antibiotic therapy does not alter mitochondrial bioenergetics in lymphocytes of patients with septic shock – A prospective cohort study

Antibiotics may trigger alterations in mitochondrial function, which has been explored in cells culture, and in animal model of sepsis. This study sought to evaluate whether antibiotic therapy affects mitochondrial bioenergetics in a 68-patients clinical study. We studied mitochondrial respiratory rates at two time points: the first day of antibiotic administration and three days after. The Δbasal, ΔCI, ΔCII respiration, and ΔBCE respiratory rates were not different between patients administered with polymyxin, vancomycin, amoxicillin-clavulanate, and azithromycin compared to those who were not administered. Specific beta-lactams are associated with specific modifications in mitochondrial respiratory endpoints – patients who used meropenem had higher delta C2 values compared to those who did not (p = 0.03). Patients who used piperacillin-tazobactam had lower delta C1 (p = 0.03) values than those who did not, but higher delta C2 values (p = 0.02). These mitochondrial metabolic signatures in isolated lymphocytes challenges the proposed effects of antibiotics in mitochondrial bioenergetics of cell cultures, but at current status have an uncertain clinical significance.

Time dependence of hydraulic parameters estimation from transient analysis of mini disc infiltrometer measurements

AbstractThe transient analysis of mini disc infiltrometer (MDI) measurements is an established method for characterising near‐surface hydraulic characteristics of soils. The reliability of hydraulic characteristics obtained from transient analysis depends on the (1) adequacy of model, (2) adequacy of data, (3) measurement time and (4) measurement footprint. The measurement time dependence recommendations are reported only for a few soil textures, initially wet samples and tension infiltrometer (TI) with a higher measurement footprint than the MDI. This study investigated the adequacy of infiltration data (using cumulative linearization [CL] and differentiated linearization [DL]) and measurement time influence on the hydraulic parameters determined from the transient analysis of MDI measurements for six soil textures. The objective of the study is to identify suitable MDI measurement durations for different soil textures for the initially dry state, considering both adequacy of data and time fractionation (measurement time influence). The data adequacy time obtained from the DL (TDL) was found to be 0.8 times less than the value obtained from CL (TCL). The marginal difference in TDL and TCL had a significant influence on the determination of infiltration equation coefficient C1 and negligible influence on coefficient C2. The time fractionation procedure adopted for identifying adequate MDI measurement time (Tm) was found to be comparable based on sorptivity (S0) and hydraulic conductivity (K0). The average Tm was also comparable with TDL and TCL with a strong positive correlation. The C2 values obtained based on Tm, TDL, and TCL were in better agreement than the corresponding C1 values. The adequate MDI measurement times identified by considering Tm, TDL, and TCL were texture dependent, ranging from 45 min for silt to 120 min for silt loam and silty clay loam. For loamy sand, it was 50 min; for sand, it was 70 min, followed by 60 min for loam.

Structural changes in trypsin induced by the bile salts: An effect of amphiphile hydrophobicity

The present study reports the multi-technique results of the interaction of a series of bile salts, sodium cholate (NaC), sodium taurocholate (NaTC), sodium deoxycholate (NaDC), and sodium taurodeoxycholate (NaTDC) with trypsin under the experimental conditions of 25 °C and pH 7.0. The interactions between trypsin and the bile salts were characterized by the surface tension measurements and various spectroscopic techniques like UV–Visible absorption, steady-state fluorescence, and circular dichroism. The results of surface tension measurements reveal a strong interaction of trypsin (50 μM) with the increasing concentration of bile salts, being higher with the bile salt of greater hydrophobicity. The critical aggregation concentration of bile salts in the presence of trypsin (C1) showed that the bile salts interact strongly with the trypsin in the order of NaTDC > NaDC > NaTC > NaC. UV–visible, steady-state fluorescence, and circular dichroism spectroscopic results confirmed significant unfolding of trypsin due to its interaction with the bile salts, the extent of which followed the same sequence as observed in the surface tension results. It could be concluded that the hydrophobic bile salts that show lower C1 values and have less delocalized charge, are more effective in unfolding the trypsin. The study would help understand the hydrophobicity-driven unfolding of proteins aided by biological surfactants like bile salts and help devise efficient proteolytic enzyme-based detergent formulations and understand the role of such amphiphiles as antimicrobial agents.

Scale-free functional brain dynamics during recovery from sport-related concussion.

Studies using blood‐oxygenation‐level‐dependent functional magnetic resonance imaging (BOLD fMRI) have characterized how the resting brain is affected by concussion. The literature to date, however, has largely focused on measuring changes in the spatial organization of functional brain networks. In the present study, changes in the temporal dynamics of BOLD signals are examined throughout concussion recovery using scaling (or fractal) analysis. Imaging data were collected for 228 university‐level athletes, 61 with concussion and 167 athletic controls. Concussed athletes were scanned at the acute phase of injury (1–7 days postinjury), the subacute phase (8–14 days postinjury), medical clearance to return to sport (RTS), 1 month post‐RTS and 1 year post‐RTS. The wavelet leader multifractal approach was used to assess scaling () and multifractal () behavior. Significant longitudinal changes were identified for , which was lowest at acute injury, became significantly elevated at RTS, and returned near control levels by 1 year post‐RTS. No longitudinal changes were identified for . Secondary analyses showed that clinical measures of acute symptom severity and time to RTP were related to longitudinal changes in . Athletes with both higher symptoms and prolonged recovery had elevated values at RTS, while athletes with higher symptoms but rapid recovery had reduced at acute injury. This study provides the first evidence for long‐term recovery of BOLD scale‐free brain dynamics after a concussion.

CHARACTERIZATION AND CORRELATION OF THE NETWORK CHAIN DENSITY TO THE PROPERTIES OF FLUOROELASTOMER RUBBER

ABSTRACTThe concentrations of triallyl isocyanurate (TAIC) in a peroxide-curable fluoroelastomer terpolymer containing 67 wt% of fluorine were varied to generate compounds of differing crosslink densities. Experimental analysis was undertaken using rheometry, hardness, stress–strain (Mooney–Rivlin), equilibrium solvent swell, and low-field nuclear magnetic resonance (NMR) using the double quantum (DQ) technique. Increasing the TAIC concentration caused a systematic rise in rheometry elastic torque, hardness, and tensile strength, whereas both elongation at break and swelling levels decreased. These results are concurrent with an enhanced overall level of crosslinking, which was confirmed by the steady increase of the Mooney–Rivlin C1 values. DQ NMR analysis using hydrogen and fluorine probes and subsequent application of fast Tikhonov regularization to the corrected intensity data were particularly useful in discerning the inhomogeneous nature of the compound morphology. The spatial distribution of the crosslink density suggests that the compound consists of small, highly crosslinked/entangled polymerized TAIC domains embedded within the elastic crosslinked matrix. A concentration of 3 phr of TAIC is optimal according to compression set testing.

Quantifying the Tensile Properties of Hevea brasiliensis – Silicone Biocomposite using Neo – Hookean Model

Incorporation of natural fibers into composites have been continuously researched in moving towards a greener environment. As environmental issues such as climate change and global warming is becoming severe, green technology is one of the ways to reduce it. Hevea brasiliensis or commonly called rubber tree produced a lot of sawdust during the conversion of the raw material into product. The sawdust is known as an agricultural waste which has no economic value. Therefore, this study for the first time attempts to utilize the Hevea brasiliensis sawdust by incorporating it with silicone rubber in the making of a new biocomposite material. The samples were prepared in two weight compositions, 0 wt% and 16 wt% in accordance to ASTM D412. Tensile properties of biocomposite was then determined using 3382 Universal Testing Machine 100kN (Instron, U.S.A., 2008). Neo Hookean hyperelastic model was employed where the material constant, C1 values were obtained. The graph plotted shows that the hyperelastic model used can mimic the deformation behavior of silicone biocomposites. The material constants are observed to increase as Hevea brasiliensis fiber are introduced into it. Hence, it can be concluded that pure silicone rubber has higher tensile strength compared to 16 wt% hevea brasiliensis – silicone biocomposite and the addition of fiber increase the stiffness properties of material produced.

Heat and Mass Transfer in 2-Propanol Droplet Evaporation: Analysis Modified Stagnant Film Model

Heat and mass transfer is an evaporation process from liquid droplet that occur in spray drying technology. So, it becomes important to understand the basic elements of spray drying, namely droplet. The formation technology involves drying is used in many industries. Various models of analogies of heat and mass transfer analogies have been formulated, with the aim of obtaining the characteristics that occur in the system. The analogy model most often used to obtain heat and mass transfer coefficients from droplet is the analogy model Ranz W. E. and Marshall W. R. The analogy has requirements, including the Lewis number (Le) which ranges in the number one. The purpose of this experiment is to compare the results obtained from the analogy of the Ranz-Marshall equation model applied to the droplet by making a modification of the C1 and C2 values that exist in the stagnant film model. In this experiment, the analysis results obtained from the modification of the stagnant film model is that the heat transfer phenomenon that occurs in droplet does not yet fully have good results. Where the value of C1 still cannot represent the value that can be used to obtain C2 properly.

Optical properties of currently used zirconia-based esthetic restorations fabricated with different techniques.

The aim was to evaluate the effects of different types of monolithic zirconia (MZ) and fabrication techniques on the optical properties of newly generated zirconia-based materials after aging. Sixty specimens (n = 10) were prepared. For the groups layering-veneering (LV), overpressing (OP), porcelain fused to zirconia (PFZ), and cutback (CB), 3Y-TZP, IPS e.max ZirCAD was prepared as the core material (0.5 ± 0.01 mm). For full-contour (FC) technique, 3Y-TZP was used for MZ-LT (low translucency) and 4Y-TZP was used for MZ-MT (medium translucency). L*, a*, b*, chroma (C), and relative translucency (RTP) were measured before (L1 *, a1 *, b1 *, C1 , RTP1 ) and after (L2 *, a2 *, b2 *, C2 , RTP2 ) UV aging. Statistical analyses were performed by one-way ANOVA with Tukey's test and paired sample t tests (P = .05). Fabrication techniques significantly affected the L*, a*, b*, C, RTP, and ΔE00 values (P ˂ .01). The highest L1 * value was found in MZ-LT; followed, in order, by OP, PFZ, LV, CB, and MZ-MT. The highest b1 * and C1 values were found in OP, while MZ-MT had the lowest values (P ˂ .05). FC had the highest RTP values for MZ-MT (13 ± 0.9 RTP1; 11.2 ± 0.9 RTP2 ), and the lowest RTP values were found for MZ-LT (8.5 ± 0.9 RTP1; 8.3 ± 1.2 RTP2 ) (P ˂ .01). Aging caused significant differences in the L*, a*, b*, C, and RTP values (P < .05). The color changes were between 0.9 and 2.1 ΔE00 . The fabrication technique significantly affected the optical properties. UV aging caused zirconia-based restorations to become darker and more yellow, red, saturated, and opaque. Fabrication techniques with different zirconia structures affected the optical properties of the restoration, even when the same shades were chosen. If more translucent restorations are needed, choosing 4-YTZP with the FC technique is better than veneering with 3-YTZP. Choosing 3-YTZP with the FC technique produces more esthetic results if brighter and more opaque restorations are needed.

Compressive mechanical properties of rat and pig optic nerve head

Glaucoma is the leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP), the primary risk factor for glaucoma, is thought to induce abnormally high strains in optic nerve head (ONH) tissues, which ultimately result in retinal ganglion cell damage and vision loss. The mechanisms by which excessive deformations result in vision loss remain incompletely understood. The ability of computational and in vitro models of the ONH to provide insight into these mechanisms, in many cases, depends on our ability to replicate the physiological environment, which in turn requires knowledge of tissue biomechanical properties. The majority of mechanical data published to date regarding the ONH has been obtained from tensile testing, yet compression has been shown to be the main mode of deformation in the ONH under elevated IOP. We have thus tested pig and rat ONH tissue using unconfined cyclic compression. The material constants C1, obtained from fitting the stress vs. strain data with a neo-Hookean material model, were 428 [367, 488] Pa and 64 [53, 76] Pa (mean [95% Confidence Interval]) for pig and rat optic nerve head, respectively. Additionally, we investigated the effects of strain rate and tissue storage on C1 values. These data will inform future efforts to understand and replicate the in vivo biomechanical environment of the ONH.

Anelastic and Microplastic Damping of an Mg–Zn–Y–Al Alloy

In this study, the Mg97Zn1Y2–Al alloy was selected as a high damping material, anelastic and microplastic damping were analyzed by studying strain amplitude-dependent damping curves of the alloy. The C1 and C2 values of the Granato–Lucke (G–L) model, the theoretical basis of anelastic damping, can be calculated for each alloy, then, the corresponding numbers of strong and weak pinners are deduced. However, since the occurrence of microplastic damping in a high strain amplitude cannot be explained by the G–L model, a new microplastic damping theory was introduced, by comparing the activation volume of the material dislocation slip, the microplastic damping capacity of the Mg97Zn1Y2–xwt%Al (x = 0.3, 1, 3) alloys at the microplastic stage are compared. The elastic and plastic deformation of the materials could be sensitively reflected by studying the damping behavior of these two stages.

Later stage gas generation in shale gas systems based on pyrolysis in closed and semi-closed systems

As a self-contained source-reservoir petroleum system, shale gas plays have different generation mechanisms from conventional natural gas plays, especially with respect to the effects of residual hydrocarbons on shale gas generation. In this study, closed-system pyrolysis experiments were conducted on a suite of residual shales obtained by the semi-closed pyrolysis of shales from the Neoproterozoic Xiamaling Formation under various conditions. The effects of oil expulsion on the geochemical characteristics of residual organic matter (both bitumen and kerogen) in shale and on shale gas generation in the high maturity stage were investigated. The results indicated that shales with high oil expulsion efficiencies should be depleted in the aliphatic fractions in residual shale. In contrast, most of the aliphatic fractions should remain in shales with low oil expulsion efficiencies. Additionally, oil expulsion can further affect the chemical and isotopic compositions of the gas generated at later stages of thermal maturation. With increasing oil expulsion efficiency, C1, C2, C3, C1–5, and C2–5 gas yields and gas wetness decrease, while C1, C2, and C3 carbon isotopic values become heavier.