Volume Ratio Research Articles

Long term variation of microphysical properties of black carbon in Beijing derived from observation and machine learning

The microphysical attributes of black carbon (BC) can determine its absorption and hygroscopic properties. However, long-term information is difficult to obtain from the field. In this study, the BC properties including mass concentration, the coating volume ratio (VR) relative to the refractory BC (rBC), the rBC diameter and the fraction of cloud condensation nuclei (CCN), are derived from a number of field experiments using a random forest model. This model effectively derives the long-term BC microphysical properties in the Beijing region from 2013 to 2020 using continuous measurements of particulate matter, gas, BC mass concentration and meteorological parameters. The results reveal notably higher BC coatings (mean VR = 7.2) and a greater fraction of CCN-like BC (51%) in the winter compared to other seasons. Following the implementation of national air pollution control measures in 2017, BC mass exhibited a substantial reduction of 60% (29%) in the winter (summer), and VR decreased by 45% (24%). Apart from the influence of meteorological variations, these can be attributed to the declined primary emissions and the gas precursors which are associated with secondary formation of BC coatings. The reduction of both BC mass loading and coatings leads to its solar absorption decreasing by 50%, and the fraction of CCN-like BC (likely in clouds) decreasing by 23%. Environmental regulation will therefore continue to reduce both direct and indirect radiative impacts of BC in this region.

The impact of experimental diabetes on intracerebral haemorrhage. A preclinical study

Although diabetes mellitus negatively affects post-ischaemic stroke injury and recovery, its impact on intracerebral haemorrhage (ICH) remains uncertain. This study aimed to investigate the effect of experimental diabetes (ED) on ICH-induced injury and neurological impairment. Sprague-Dawley rats were induced with ED 2 weeks before ICH induction. Animals were randomly assigned to four groups: 1)Healthy; 2)ICH; 3)ED; 4)ED-ICH. ICH and ED-ICH groups showed similar functional assessment. The ED-ICH group exhibited significantly lower haemorrhage volume compared with the ICH group, except at 1 mo. The oedema/ICH volume ratio and cistern displacement ratio were significantly higher in the ED-ICH group. Vascular markers revealed greater expression of α-SMA in the ED groups (ED and ED-ICH) compared with ICH. Conversely, the ICH groups (ED-ICH and ICH) exhibited higher levels of VEGF compared to the healthy and ED groups. An assessment of myelin tract integrity showed an increase in fractional anisotropy in the ED and ED-ICH groups compared with ICH. The ED group showed higher cryomyelin expression than the ED-ICH and ICH groups. Additionally, the ED groups (ED and ED-ICH) displayed higher expression of MOG and Olig-2 than ICH. As for inflammation, MCP-1 levels were significantly lower in the ED-ICH groups compared with the ICH group. Notably, ED did not aggravate the neurological outcome; however, it results in greater ICH-related brain oedema, greater brain structure displacement and lower haemorrhage volume. ED influences the cerebral vascularisation with an increase in vascular thickness, limits the inflammatory response and attenuates the deleterious effect of ICH on white matter integrity.

In Vitro Digestion-In Situ Absorption Setup Employing a Physiologically Relevant Value of the Membrane Surface Area/Volume Ratio for Evaluating Performance of Lipid-Based Formulations: A Comparative Study with an In Vitro Digestion-Permeation Model.

The aim of this study is to establish and test an in vitro digestion-in situ absorption model that can mimic in vivo drug flux by employing a physiologically relevant value of the membrane surface area (S)/volume (V) ratio for accurate prediction of oral drug absorption from lipid-based formulations (LBFs). Three different types of LBFs (Type IIIA-MC, Type IIIA-LC, and Type IV) loaded with cinnarizine (CNZ), a lipophilic weak base with borderline permeability, and a control suspension were prepared. Subsequently, a simultaneous in vitro digestion-permeation experiment was conducted using a side-by-side diffusion cell with a dialysis membrane having a low S/V value. During digestion, CNZ partially precipitated for Type IV, while it remained solubilized in the aqueous phase for Type IIIA-MC and Type IIIA-LC in the donor compartment. However, in vitro drug fluxes for Type IIIA-MC and Type IIIA-LC were lower than those for Type IV due to the reduced free fraction of CNZ in the donor compartment. In pharmacokinetic studies, a similar improvement in in vivo oral exposure relative to suspension was observed, regardless of the LBFs used. Consequently, a poor correlation was found between in vitro permeation and areas under the plasma concentration-time curve (AUCoral) (R2 = 0.087). A luminal concentration measurement study revealed that this discrepancy was attributed to the extremely high absorption rate of CNZ in the gastrointestinal tract compared to that across a dialysis membrane evaluated by the in vitro digestion-permeation model, i.e., the absorption of CNZ in vivo was completed regardless of the extent of the free fraction, owing to the rapid removal of CNZ from the intestine. Subsequently, we aimed to predict the oral absorption of CNZ from the same formulations using a model that demonstrated high drug flux by employing the physiologically relevant S/V value and rat jejunum segment as an absorption sink (for replicating in vivo intestinal permeability). Predigested formulations were injected into the rat intestinal loop, and AUCloop values were calculated from the plasma concentration-time profiles. A better correlation was found between AUCloop and AUCoral (R2 = 0.72), although AUCloop underestimated AUCoral for Type IV due to the precipitation of CNZ during the predigestion process. However, this result indicated the importance of mimicking the in vivo drug absorption rate in the predictive model. The method presented herein is valuable for the development of LBFs.

Glass bead system to study mycotoxin production of Aspergillus spp. on corn and rice starches

Mycotoxin production by aflatoxin B1 (AFB1) -producing Aspergillus flavus Zt41 and sterigmatocystin (ST) -hyperproducer Aspergillus creber 2663 mold strains on corn and rice starch, both of high purity and nearly identical amylose-amylopectin composition, as the only source of carbon, was studied. Scanning electron microscopy revealed average starch particle sizes of 4.54 ± 0.635 µm and 10.9 ± 2.78 µm, corresponding to surface area to volume ratios of 127 1/µm for rice starch and 0.49 1/µm for corn starch. Thus, a 2.5-fold difference in particle size correlated to a larger, 259-fold difference in surface area. To allow starch, a water-absorbing powder, to be used as a sole food source for Aspergillus strains, a special glass bead system was applied. AFB1 production of A. flavus Zt41 was determined to be 437.6 ± 128.4 ng/g and 90.0 ± 44.8 ng/g on rice and corn starch, respectively, while corresponding ST production levels by A. creber 2663 were 72.8 ± 10.0 µg/g and 26.8 ± 11.6 µg/g, indicating 3–fivefold higher mycotoxin levels on rice starch than on corn starch as sole carbon and energy sources.Key points• A glass bead system ensuring the flow of air when studying powders was developed.• AFB1 and ST production of A. flavus and A. creber on rice and corn starches were studied.• 3–fivefold higher mycotoxin levels on rice starch than on corn starch were detected.

Deadwood enrichment in Fennoscandian spruce forests – New results from the EVO experiment

In Fennoscandian forests, evidence on the effects of variable tree retention, prescribed burning and deadwood creation on deadwood quantity and quality is still scarce. We studied the effects of prescribed burning, tree retention and downed wood creation on the deadwood profile in managed boreal Norway spruce forest stands over a 16-year period. The stand scale treatments of the experiment included cuttings with a constant volume of dispersed retention trees (50 m3 ha-1, ca. 200 trees per ha), and three levels of downed deadwood creation (5, 30 and 60 m3 ha-1), in both upland and paludified biotopes of Myrtillus site type, with or without prescribed burning, with three replicates each.After 16 years since the treatments, the diverse deadwood profiles with varying distribution by decay class were formed. The volume of deadwood varied from 9 to 107 m3 ha-1 with a mean of 65 m3 ha-1. The index of deadwood diversity was positively influenced by prescribed burning and negatively influenced by deadwood creation. The volume of all deadwood and coarse woody debris (CWD), volume and number of logs, as well as dead to live volume ratio increased after prescribed burning and with the level of deadwood creation. The positive effect of deadwood creation on the total CWD volume was higher in the upland biotopes than in the paludified ones. The highest amounts of all deadwood, CWD and logs were recorded in the upland biotopes after prescribed burning without deadwood creation. Our findings highlight the impact of tree retention with prescribed burning and deadwood creation in diversifying deadwood profile and maintaining deadwood continuum for decades.

Optimization of the solvent system used to prepare cannabis inflorescence samples for cannabidiol and Δ9-tetrahydrocannabinol quantification using D-optimal design

The solvent most commonly used to prepare cannabis inflorescence samples is a mixture of methanol and chloroform (9:1), which poses a health hazard. This study aimed to develop a solvent system that maximizes the extraction of two major cannabinoids, cannabidiol (CBD) and Δ9-tetrahydrocannabinol (Δ9-THC), with superior performance to conventional solvents. The cannabinoid content was determined using high-performance liquid chromatography. The stability of these two cannabinoids in the optimal solvent system was also evaluated. The volume ratios of acetonitrile, methanol, and water were varied for extracting cannabinoids from two cannabis cultivars, Hang Kra Rog Phu Phan and Charlotte’s Angel, based on a D-optimal design. The solvent system developed in this study showed superior extraction efficiency to acetonitrile, as specified in the Thai Herbal Pharmacopoeia, and the methanol:chloroform mixture (9:1), as specified in the United Nations Office on Drugs and Crime manual. The optimal solvent system that provided the highest cannabinoid content consisted of acetonitrile, methanol, and water at a volume ratio of 0.511:0.289:0.200. This solvent system could extract 0.141 % ± 0.023 % of CBD and 3.255 % ± 0.511 % of Δ9-THC from the Hang Kra Rog Phu Phan cultivar, and 2.120 % ± 0.143 % of CBD and 3.813 % ± 0.219 % of Δ9-THC from the Charlotte’s Angel cultivar. The stability of cannabinoids in the optimal solvent system was comparable to that of the methanol:chloroform mixture (9:1) but superior to acetonitrile when stored at 4 °C and − 20 °C for 28 days. In summary, the optimal solvent system developed in this study is less toxic than existing systems and can be valuable for extracting cannabinoids from cannabis during inflorescence sample preparation for analyzing their content.

Simultaneous assessment of blood flow and myelin content in the brain white matter with dynamic [11C]PiB PET: a test-retest study in healthy controls.

Exploring the relationship between oxygen supply and myelin damage would benefit from a simultaneous quantification of myelin and cerebral blood flow (CBF) in the brain's white matter (WM). To validate an analytical method for quantifying both CBF and myelin content in the WM using dynamic [11C]PiB positron emission tomography (PET). A test-retest study was performed on eight healthy subjects who underwent two consecutive dynamic [11C]PiB-PET scans. Three quantitative approaches were compared: simplified reference tissue model 2 (SRTM2), LOGAN graphical model, and standardized uptake value ratio (SUVR). The sensitivity of methods to the size of the region of interest was explored by simulating lesion masks obtained from 36 subjects with multiple sclerosis. Reproducibility was assessed using the relative difference and interclass correlation coefficient. Repeated measures correlations were used to test for cross-correlations between metrics. Among the CBF measures, the relative delivery (R1) of the simplified reference tissue model 2 (SRTM2) displayed the best reproducibility in the white matter, with a strong influence of the size of regions analyzed, the test-retest variability being below 10% for regions above 68 mm3 in the supratentorial white matter. [11C]PiB PET-derived proxies of CBF demonstrated lower perfusion of white matter compared to grey matter with an overall ratio equal to 1.71 ± 0.09 when the SRTM2-R1 was employed. Tissue binding in the white matter was well estimated by the Logan graphical model through estimation of the distribution volume ratio (LOGAN-DVR) and SRTM2 distribution volume ratio (SRTM2-DVR), with test-retest variability being below 10% for regions exceeding 106 mm3 for LOGAN-DVR and 300 mm3 for SRTM2-DVR. SRTM2-DVR provided a better contrast between white matter and grey matter. The interhemispheric variability was also dependent on the size of the region analyzed, being below 10% for regions above 103 mm3 for SRTM2-R1 and above 110 mm3 for LOGAN-DVR. Whereas the 1 to 8-minute standardized uptake value ratio (SUVR1-8) showed an intermediary reproducibility for CBF assessment, SUVR0-2 for perfusion or SUVR50-70 for tissue binding showed poor reproducibility and correlated only mildly with SRTM2-R1 and LOGAN-DVR estimations respectively. [11C]PiB PET imaging can simultaneously quantify perfusion and myelin content in WM diseases associated with focal lesions. For longitudinal studies, SRTM2-R1 and DVR should be preferred over SUVR for the assessment of regional CBF and myelin content, respectively. European Union Clinical Trials Register EUDRACT; EudraCT Number: 2008-004174-40; Date: 2009-03-06; https//www.clinicaltrialsregister.eu ; number 2008-004174-40.

Experimental and analytical study on eccentrically loaded Fiber concrete columns reinforced longitudinally with GFRP bars

In this paper, experiments were carried out to analyze the behavior of the square columns reinforced longitudinally by GFRP bars along with different ratios of hooked end fibers under eccentric compressive loading. Eight short square columns with a cross-section dimension of 150x150mm and a height of 1200 mm, were fabricated to conduct the experimental program. A 150 mm enlargement in column-cross at both ends was considered to develop an eccentric axial load. The columns were tested under different load eccentricity ratios (0.26, 0.5, 1). Different tie spacings (50, 100, 120) mm. Different ratios of steel fibers 0 %, 0.5 %, and 1 % were incorporated into the concrete mix. It was observed that columns with steel fibers demonstrated good characteristics, including higher ultimate load, increased ultimate deflection, and enhanced ductility and toughness compared to the columns without steel fibers due to multiple cracking behaviors. The ductility of the columns reinforced with GFRP bars was enhanced by 46.8 %, and 68 % for steel fiber volume ratios of 0.5 % and 1 %, respectively. The energy absorption was increased by 42 % and 77 % for steel fibers ratios of 0.5 % and 1 %, respectively. When GFRP bars were used as longitudinal reinforcement, there was an improvement in the bond behavior between the concrete and the GFRP bars. All concrete columns reinforced by GFRP bars failed due to flexure-compression failure. There was no observed rupture of GFRP bars during the experimental test and the maximum strain did not reach 40 % of their ultimate strain capacity. Nonlinear Finite Element analysis was conducted to simulate the behavior of tested columns. The equations from previous studies and the codes were established to predict the nominal peak capacity of columns considering all parameters. In general, there was a reasonable level of agreement observed between the experimental data and the theoretical results determined for seventy-column specimens in the current study and from previous studies in the literature.

Ultrasound-assisted intensification of Pickering interfacial biocatalysis preparation of vitamin A aliphatic esters

A novel approach to ultrasound-assisted Pickering interfacial biocatalysis (PIB) has been proposed and implemented for the efficient enzymatic transesterification production of vitamin A fatty acid esters. This is the first instance of exploiting the synergistic effect of ultrasound and the bifunctional modification of enzyme supports to accelerate biocatalytic performance in PIB systems. The optimal conditions were determined to be ultrasound power of 70 W, on/off time of 5 s/5 s, substrate molar ratio of 1:1, enzyme addition of 2 %, and a volume ratio of n-hexane to PBS of 3:1, a temperature of 40 °C, and a time of 30 min. The application of ultrasound technology not only improved lipase activity but also allowed for a reduction in emulsion droplet size to enhance interfacial mass transfer.Bifunctional modification of silica-based supports enhanced stability of immobilized enzymes by increasing hydrogen bonding while maintaining the active interface microenvironment. Compared with a non-ultrasound-assisted PIB system stabilized by mono-modified immobilized enzyme particles, the catalytic efficacy (CE) of the novel system reached 8.18 mmol g−1 min−1, which was enhanced by 3.33-fold, while the interfacial area was found to have increased by 17.5-fold. The results facilitated the conversion of vitamin A palmitate (VAP), vitamin A oleate (VAO), vitamin A linoleate (VAL), and vitamin A linolenate (VALn), with conversion rates of approximately 98.2 %, 97.4 %, 96.1 %, and 94.7 %, respectively. This represents the most efficient example that has been reported to our knowledge. Furthermore, the system demonstrated improved reusability, with a conversion rate of 62.1 % maintained even after 10 cycles. The findings presented in this paper provide valuable insights into an efficient and conveniently promising protocol for the development of PIB systems.

Development of an HPLC device with water/acetonitrile with NaCl mixed solution that induces a phase-separation multiphase flow as the eluent in the separation column.

We developed a novel HPLC device where the phase-separation multiphase flow worked as the eluent in the separation column by using a water/acetonitrile/ethyl acetate triple mixed solution as a dual-phase-separation solution. Dual-phase-separation solutions form a phase-separation multiphase flow in a microscopic space. The new separation mechanism in the HPLC is called phase-separation mode. In this study, we used water and acetonitrile with NaCl mixed solution as a dual-phase-separation solution instead of the triple mixed solution. Octadecylsilyl (ODS)-modified particle- and porous silica particle-packed separation columns were united with the HPLC device for phase-separation mode caused by phase-separation multiphase flow. NA (1-naphthol) and NDS (2,6-naphthalenedisulfonic acid) were analyzed by the device as model sample. Using the water and acetonitrile with NaCl mixed solution at the solvent volume ratio of 5:5, NA and NDS were not separated on either column at 25°C. On the other hand, they were separated with the order NDS and NA on the ODS column and separated with the order NA and NDS on the silica column in phase-separation mode at 0°C. We discuss the separation mechanism of phase-separation mode using the water and acetonitrile with NaCl mixed solution at 0°C.

Aggregate Risk and Lending Decisions in the Interbank Market

AbstractWe introduce a novel measure of the market‐wide rik of the interbank market: the total (across all banks) uncollateralized/collateralized lending volume ratio: . This measure is based on the intuition that lender banks should use less (more) uncollateralized (collateralized) lending when aggregate risk increases, after controlling for banks’ features and market conditions that might affect (e.g., banks’ credit risk, cross‐border inflows, supply–demand heterogeneity, and funding costs, among others). This is because collateralized loans are safer than uncollateralized ones after an interbank market‐wide collapse. Actually, we show that modifies the future lending decisions and net lending holdings of individual banks.

Green Synthesis of Silver Nanoparticles with Snake Fruit Peel Extract: A Preliminary Study For Optimization of The Preparation Technique

In Indonesia, the pulp of snake fruit is consumed while the peel remains unused. In this context, the phytochemical content of snake fruit aqueous extract was used as a reducing and capping agent in the preparation of silver nanoparticles (AgNPs). According to the phytochemical screening, snake fruit peel containing alkaloids, flavonoids, tannins, saponins, and polyphenols was used to synthesize AgNPs. Therefore, this research aimed to optimize the synthesis of AgNPs using snake fruit peel extract (Salacca zalacca) in terms of synthesis time, temperature and phytochemical screening. AgNPs were successfully synthesized using a volume ratio of 2:15 (20 mL of 1.00 mM AgNO3 to 150 mL of snake fruit peel extract) in a sealed container in a dark room. Furthermore, characterization was carried out using a UV-Vis spectrum and Fourier Transform Infrared Spectroscopy (FTIR). The UV-Vis spectrum characterization in a solution incubated for 30 minutes at 30 °C with a concentration of 1.00 mM AgNO3 was differentiated at a wavelength of 410 nm with an absorbance of 2.361. According to the FTIR characterization, there was an increase in the intensity of the O – H functional groups in the AgNPs solution compared to snake fruit peel extract. The results showed that the synthesis of AgNPs from snake fruit peel extract was optimal at a concentration of 1.00 mM AgNO3 at 30 °C and 30 minutes of incubation.

Grading of skull base meningiomas by combined perfusion: arterial spin labeling and T2* dynamic susceptibility perfusion

BackgroundConventional MRI has no distinction between high- and low-grade meningiomas, which has a crucial for choice of therapeutic plan, especially skull base meningiomas which need more meticulous endoscopy-approached surgery. The aim of our study was to evaluate role of perfusion by arterial spin labeling and dynamic susceptibility perfusion in grading of skull base meningiomas.ResultsThe relative arterial spin labeling (ASL), tumor blood flow (TBF), and tumor blood volume (TBV) ratios showed significant differences between low- and high-grade meningiomas.ConclusionsMRI perfusion is a useful in differentiation between low- and high-grade meningiomas. There is significant correlation between ASL and DSC perfusion supporting possibility of using ASL in clinical practice as an alternative technique to DSC perfusion, particularly for patients with renal impairment where no contrast injection needed.

Porosity Characteristics of Coal Seams and the Control Mechanisms of Coal Petrology in the Xishanyao Formation in the Western Part of the Southern Junggar Basin

The porosity characteristics of coal seams serve as a pivotal factor in assessing the development potential of coalbed methane (CBM) resources, significantly influencing the adsorption and permeability capabilities of coal reservoirs, as well as the accumulation, entrapment, and preservation of CBM. In this study, we focused on the coal seams of the Xishanyao Formation in the western part of the southern Junggar Basin (NW China). By leveraging the complementarity of nuclear magnetic resonance (NMR), low-temperature liquid nitrogen experiments, and high-pressure mercury intrusion porosimetry (MIP) in spatial exploration range and precision, we conducted a comprehensive analysis to achieve a fine description of porosity characteristics. Furthermore, we explored the coal petrology factors controlling the pore characteristics of the Xishanyao Formation, aiming to provide geological evidence for the selection of favorable areas and the development potential evaluation of CBM in the study area. The results indicate the following: (1) The total pore volume of the coal samples is 6.318 × 10−3 cm3/g on average, and the micropore volume accounts for a relatively high proportion (averaging 44.17%), followed by the fine pores (averaging 39.41%). The average porosity is approximately 3.87%, indicating good gas storage and connectivity of the coal seams, albeit with some heterogeneity. The coal reservoir is dominated by micropores and fine pores with diameters less than 100 nm, and the pore structure is characterized by low pore volume and high pore area. (2) The pore structure is influenced by both the coalification degree and the coal maceral. Within the range of low coalification, porosity increases with the increase in coalification degree. Building upon this, an increase in the vitrinite content promotes the development of micropores and fine pores, while an increase in the inertinite content promotes the development of meso–macropores. The clay mineral content exhibits a negative correlation with the adsorption pore volume ratio and a positive correlation with the seepage pore volume ratio.

Influence of electrolyte to silicon electrode volume ratio on the capacity of next generation lithium ion cells at low temperature

Silicon electrodes are being investigated as potential high-capacity replacements for graphite electrodes in lithium-ion batteries. Various factors affecting silicon electrodes need to be understood to maintain increased capacity and high performance at subzero temperatures. This work investigates electrode thickness and volume of electrolyte used that can affect performance of a copper modified silicon electrode at −20 °C. When electrolyte volume is large compared to electrode volume (20:1 ratio), the performance of these cells at low temperature is noticeably improved, retaining approximately 400 mAh/g capacity at −20 °C after 50 cycles.

Anesthesia blunts carbon dioxide effects on glymphatic cerebrospinal fluid dynamics in mechanically ventilated rats.

Impaired glymphatic clearance of cerebral metabolic products and fluids contribute to traumatic and ischemic brain oedema and neurodegeneration in preclinical models. Glymphatic perivascular cerebrospinal fluid (CSF) flow varies between anesthetics possibly due to changes in vasomotor tone and thereby in the dynamics of the periarterial CSF-containing space. To better understand the influence of anesthetics and carbon dioxide levels on CSF dynamics, we studied the effect of periarterial size modulation on CSF distribution by changing blood carbon dioxide levels and anesthetic regimens with opposing vasomotor influences - vasoconstrictive ketamine-dexmedetomidine (K/DEX) and vasodilatory isoflurane (ISO). End-tidal carbon dioxide (EtCO2) was modulated with either supplemental inhaled carbon dioxide to reach hypercapnia (EtCO2 80 mmHg) or hyperventilation (EtCO2 20 mmHg) in tracheostomized and anesthetized female rats. Distribution of intracisternally infused radiolabeled CSF tracer 111In-diethylamine pentaacetate was assessed for 86 minutes in 1) normoventilated (EtCO2 40 mmHg) K/DEX, 2) normoventilated ISO, 3) hypercapnic K/DEX, and 4) hyperventilated ISO groups using dynamic whole-body single-photon emission tomography. CSF volume changes were assessed with magnetic resonance imaging. Under normoventilation, cortical CSF tracer perfusion, perivascular space size around middle cerebral arteries (MCAs), and intracranial CSF volume were higher under K/DEX compared with ISO (cortical Cmax ratio 2.33 [95% CI 1.35 to 4.04], perivascular size ratio 2.20 [95% CI 1.09 to 4.45], and intracranial CSF volume ratio 1.90 [95% CI 1.33 to 2.71]). Under ISO, tracer was directed to systemic circulation. Under K/DEX, the intracranial tracer distribution and CSF volume were uninfluenced by hypercapnia compared with normoventilation. Intracranial CSF tracer distribution was unaffected by hyperventilation under ISO despite a 28% increase in CSF volume around MCAs. K/DEX and ISO overrode carbon dioxide as a regulator of CSF flow. K/DEX could be used to preserve CSF space and dynamics in hypercapnia whereas hyperventilation was insufficient to increase cerebral CSF perfusion under ISO.

Characteristics of hydrogen enrichment on RNG combustion under various engine speeds in a retrofitted gas engine

Renewable natural gas (RNG) is attractive for energy policy goals in the world. A regional system is designed to explore RNG combustion for power generation in localities. Generally, 50 % methane (CH4) and 50 % carbon dioxide (CO2) in volume are utilized to represent RNG for investigations. However, CO2 reduces the burning rate and narrows the flammability limits, thus decreasing the engine thermal efficiency. Therefore, how to increase the thermal efficiency of RNG combustion through adding H2 or changing engine speed is the main task here. This study investigates a port fuel injection (PFI) engine fueled with hydrogen (H2) blended into the RNG. In order to obtain the higher efficiency, the effect of engine speed on combustion characteristics should be clarified as well as H2 influence demonstrated. Therefore, 1500, 2000 and 2500 revolutions per minute (rpm) of engine speed were tested. When H2 was added, the volume percentage changed from 5 % to 20 % by keeping the volume ratio of CH4 and CO2 at 1:1. Finally, combustion characteristics of CH4, CH4+CO2 and CH4+CO2+H2 were compared and discussed. Results showed that compared with H2, engine speed could only increase the efficiency slightly. “Arched” and “fish-hook” curves are fitted respectively to select the optimal working region. Through cylinder pressure analysis, engine speed could enlarge the Pmax only at some certain but increase coefficient of variation (COV) gradually. However, H2 increases Pmax but decreases COV significantly. Moreover, NOx decreases gradually with engine speed owing to the short reaction duration in combustion. However, NOx increases again with higher H2 concentration. Among the current conditions, for higher efficiency and lower NOx, three conditions are finally selected to be recommended for running.

Internal Force Mechanism of Pisha Sandstone as a Soil Amendment to Improve Sandy Soil Structural Stability in Mu Us Sandy Land

Compounding Pisha sandstone (PSS) with sandy soil in Mu Us Sandy Land is a viable agronomical measure to effectively reduce soil erosion and improve soil quality due to the complementary characters and structures of the two materials. Aggregate stability is an important indicator to assess sandy soil erosion resistance and quality, which could be largely affected by soil surface electrochemical properties and particle interaction forces. However, the effect of the compound ratio and particle interaction forces on the aggregate stability of compound soils with Pisha sandstone and sandy soil is still unclear. Therefore, in this study, the electrochemical properties, particle interaction forces, and their effects on the aggregate stability of PSS and sandy soil at five volume ratios (0:1, 1:5, 1:2, 1:1, and 1:0) were determined to clarify the internal force mechanism of PSS to increase sandy soil structural stability in a 10-year field experiment. Experiments were measured by a combined method for the determination of surface properties and aggregate water stability. A ten-year field study revealed that the incorporation of Pisha sandstone significantly enhanced the soil organic carbon (SOC) and cation exchange capacity (CEC) (p < 0.05), while the CEC value notably increased from 4.68 to 13.76 cmol·kg−1 (p < 0.05). The soil surface potential (absolute value) and the electric field intensity gradually decreased with the increase in the Pisha sandstone content. For the compound soil particle interaction force, the addition of Pisha sandstone enhanced the van der Waals attraction force, reduced the net repulsive force between compound soil particles, and promoted the agglomeration of aeolian sandy soil. The overall trend of the aggregate breaking strength of compound soils under different addition ratios of PSS was 1:0 > 1:1 > 0:1 > 1:5 > 1:2. When the Pisha sandstone content in the compound soils was <50%, the aggregate stability was mainly influenced by compound soil particle interaction forces, and the interaction force increase was the key reason for the aggregate breakdown. When the Pisha sandstone content in the compound soils was ≥50%, the aggregate stability was affected by the combined effects of the compound soil particle composition and particle interaction forces. These results indicate that PSS addition ratios and particle interaction force are important factors affecting the structural stability of compound soils, in which the volume ratio of PSS to sandy soil of 1:2 is the appropriate ratio. Our study provides some theoretical references for further understanding of the compound soil structure improvement and sandy soil erosion control in Mu Us Sandy Land.

#780 “In vivo” difference in ultrafiltration coefficient between two same membrane dialyzers: bigger surface area accounts for better dialysis outcomes?

Abstract Background and Aims Ultrafiltration coefficient (KUF) is a measure of dialyzer permeability to water, given by manufacturers, and expressed in milliliters/hour/mmHg of pressure gradient. Most dialyzers used at this moment are classified as high-flow as having a KUF >20 mL/h/mmHg. KUF value of a dialyzer is an “in vitro” measure which does not correlate with “in vivo” measure, stated to be 5-30% less than theoretical KUF. According to this statement, we wanted to study differences between theoretical and real KUF of two dialyzers with the same membrane composition and different surface area. For this task, we chose 2 dialyzers of usual use in our dialysis unit: FX CorDiax 1000 and FX CorDiax 80 (®FMC). These dialyzers have a main difference in Surface area: 2.3 and 1.8 m2, respectively, and have a theoretical KUF of 76 and 64 mL/h/mmHg. Also, both dialyzers differ in intern diameter (210 vs 185 µm). Method A prospective, not randomized trial was conducted. Inclusion criteria were patients in chronic dialysis at our center, in postdilutional online hemodiafiltration with a FX1000 dialyzer. All patients were informed and accepted freely signing an informed consentment. On 2 consecutive weeks, the intermediate dialysis session of the week was performed in a DBB-EXA dialysis monitor (®Nikkiso), first with a FX CorDiax 1000 and next week with a FX CorDiax 80, with habitual patient dialysis parameters (240 minutes). Blood tests were taken previous and after the session to evaluate clearance differences between both filters. During the session, pressure and flow data was recorded, with an “in vivo” KUF measurement given by the monitor. Results Dialysis sessions were performed in 12 patients who met inclusion criteria. Data results are shown in Table 1. Significant differences between FX CorDiax 1000 and FX CorDiax 80 were observed in prefilter pressure (p 0.008), convective volume (p 0.034), prolactin reduction ratio (p 0.012), “in vivo” KUF/ “in vitro” KUF ratio (p 0.002). “In vivo” KUF graphic given by the monitor showed a logarithmic function curve, with a stabilization between the 2nd and 3rd hour of the session. Conclusion In our study, measurement of “in vivo” KUF by Nikkiso monitor showed a slow decrease after 2nd hour of session, probably related with protein cake of membrane pores. “In vivo” KUF measure was approximately a 40-45% of theoretical value given by manufacturer. The “in vivo” KUF/ “in vitro” KUF ratio was higher for the smaller dialyzer, which probably means a higher optimization of its surface area with usual dialysis sessions. Convective volume and prolactin reduction ratio, as parameters of dialysis efficacy, are higher in the dialyzer with higher surface area and inner intern diameter.

The Challenge of E-Spinning Sub-Millimeter Tubular Scaffolds-A Design-of-Experiments Study for Fiber Yield Improvement.

In tissue engineering, electrospinning has gained significant interest due to its highly porous structure with an excellent surface area to volume ratio and fiber diameters that can mimic the structure of the extracellular matrix. Bioactive substances such as growth factors and drugs are easily integrated. In many applications, there is an important need for small tubular structures (I.D. < 1 mm). However, fabricating sub-millimeter structures is challenging as it reduces the collector area and increases the disturbing factors, leading to significant fiber loss. This study aims to establish a reliable and reproducible electrospinning process for sub-millimeter tubular structures with minimized material loss. Influencing factors were analyzed, and disturbance factors were removed before optimizing control variables through the design-of-experiments method. Structural and morphological characterization was performed, including the yield, thickness, and fiber arrangement of the scaffold. We evaluated the electrospinning process to enhance the manufacturing efficiency and reduce material loss. The results indicated that adjusting the voltage settings and polarity significantly increased the fiber yield from 8% to 94%. Variations in the process parameters also affected the scaffold thickness and homogeneity. The results demonstrate the complex relationship between the process parameters and provide valuable insights for optimizing electrospinning, particularly for the cost-effective and reproducible production of small tubular diameters.