Experimental Model For Study Research Articles

An experimental and kinetic modeling study on the low-temperature oxidation, ignition delay time, and laminar flame speed of a surrogate fuel for RP-3 kerosene

The low-temperature oxidation (under the conditions of the initial pressure of 0.1 MPa, equivalence ratio of 0.5 and 1.0, temperature range of 550–1100 K), ignition delay times (under the conditions of the equivalence ratio of 0.5, 1.0, 1.5, initial pressure of 0.1, 0.3 MPa, temperature range of 1000–1700 K) and laminar flame speeds (under the conditions of the initial temperature of 400, 420, 450, 480 K, equivalence ratio of 0.7–1.4 and pressure of 0.1, 0.3 MPa) of RP-3 kerosene and its surrogate fuel (including 14% n-decane/10% n-dodecane/30% isohexadecane/36% methylcyclohexane/10% toluene, by mole fraction) were experimental tested in the jet-stirred reactor, shock tube, and constant volume combustion bomb, respectively. The results show that the low-temperature oxidation, ignition delay times, and laminar flame speeds of the surrogate fuel are in good agreement with those of RP-3 kerosene. Meanwhile, through the reaction class-based global sensitivity analysis, decoupling methodology, and multi-objective genetic algorithm, the reduced reaction mechanism of the surrogate fuel (including 181 species and 872 reactions) was established. The results show that this reduced reaction mechanism can well predict the low-temperature oxidation, ignition delay times, and laminar flame speeds of RP-3 kerosene and the surrogate fuel.

Experimental and kinetic modeling studies of 2-acetylfuran pyrolysis at atmospheric pressure

Furan-based derivatives are promising biomass fuels that may be used directly in internal combustion engines as alternative fuels or as additives to fossil fuels. In this work, the experimental studies of 2-acetylfuran (AF2) pyrolysis were carried out in a jet-stirred reactor in the temperature range of 770 – 1130 K and at the pressure of 760 Torr, using synchrotron vacuum ultraviolet photo-ionization mass spectrometry, coupled with gas chromatography. Key pyrolysis intermediates such as methane, ethylene, acetylene, ketene, vinylacetylene, cyclopentadiene, ethynylketene, 2-methylfuran, furfural, carbon monoxide and isomers such as allene/propyne, furan/vinylketene, benzene/fulvene, etc., were identified and quantified. The potential energy surfaces of AF2 unimolecular decomposition reactions were calculated at CBS-QB3 level. The temperature- and pressure-dependent rate constants of the relevant reactions were calculated by solving the master equation based on Rice-Ramsperger-Kassel-Marcus theory. A detailed pyrolysis kinetics of AF2 was developed based on the previous combustion models of 2-methylfuran and was validated against the current experimental results. Rate of production and sensitivity analysis showed that the main consumption pathways of AF2 pyrolysis under atmospheric pressure are unimolecular decomposition reactions, leading to 2-furyl + acetyl and furoyl + methyl, and hydrogen atom-addition reaction to C(5), leading to 2,3-dihydro-5-acetyl-3-furyl, accounting at 1070 K for 25.1%, 13.2% and 20.7% of AF2 consumption, respectively (the remaining 41.0% are due to minor reaction channels contributing < 10% each). At this temperature, the total AF2 consumption is 73%. The contributions of ipso-substitution reactions by methyl and by hydrogen atom to AF2 consumption were comparable.

Removal of Cu2+, Cd2+, and Pb2+ from aqueous solution by fabricated MIL-100(Fe) and MIL-101(Cr): Experimental and molecular modeling study

In this study, two metal-organic frameworks [MIL-100(Fe) and MIL-101(Cr)] are fabricated and investigated to determine their ability to remove Cu2+, Cd2+, and Pb2+ from aqueous solution. MIL-100(Fe) and MIL-101(Cr) exhibited fast adsorption kinetics, achieving equilibrium in approximately 0.5 h. To evaluate the adsorption capacities of MIL-100(Fe) and MIL-101(Cr), the experimental data was fit to the Linear, Freundlich, and Langmuir isotherm models. Based on the sum of the squared error analysis, the experimental data fit most closely to the Freundlich model, followed closely by the Linear isotherm model. However, the values for the Freundlich parameter n were close to 1, which suggests that the adsorption followed the Linear isotherm model. The KLIN adsorption affinity coefficient [(mg/g)/(mg/L)] for the Linear isotherm model was the largest for Cu2+ (KLIN, MIL-100(Fe) = 14.9; KLIN, MIL-101(Cr) = 60.3), followed by Cd2+ (KLIN, MIL-100(Fe) = 12.9; KLIN, MIL-101(Cr) = 11.5) and Pb2+ (KLIN, MIL-100(Fe) = 4.44; KLIN, MIL-101(Cr) = 8.33). Characterization data of MIL-100(Fe) and MIL-101(Cr) showed specific surface areas of 1586 m2/g and 2505 m2/g for MIL-100(Fe) and MIL-101(Cr), respectively, along with the presence of various functional groups, including carboxyl and phenyl groups. Considering this data alongside the local energy decomposition analysis that was performed using molecular modeling, electrostatic interactions were determined to be the dominant adsorption mechanism for the removal of Cu2+, Cd2+, and Pb2+ by MIL-100(Fe) and MIL-101(Cr), which is consistent with other, similar adsorption studies. This study shows that MIL-100(Fe) and MIL-101(Cr) are effective adsorbents for the removal of heavy metals from aqueous solution.

Monitoring Mitochondrial Partial Oxygen Pressure During Cardiac Arrest and Extracorporeal Cardiopulmonary Resuscitation. An Experimental Pilot Study in a Pig Model.

Introduction: Ischemia and reperfusion are crucial in determining the outcome after cardiac arrest and can be influenced by extracorporeal cardiopulmonary resuscitation (ECPR). The effect of ECPR on the availability and level of oxygen in mitochondria remains unknown. The aim of this study was to find out if skin mitochondrial partial oxygen pressure (mitoPO2) measurements in cardiac arrest and ECPR are feasible and to investigate its course.Materials and Methods: We performed a feasibility test to determine if skin mitoPO2 measurements in a pig are possible. Next, we aimed to measure skin mitoPO2 in 10 experimental pigs. Measurements were performed using a cellular oxygen metabolism measurement monitor (COMET), at baseline, during cardiac arrest, and during ECPR using the controlled integrated resuscitation device (CIRD).Results: The feasibility test showed continuous mitoPO2 values. Nine experimental pigs could be measured. Measurements in six experimental pigs succeeded. Our results showed a delay until the initial spike of mitoPO2 after ECPR initiation in all six experimental tests. In two experiments (33%) mitoPO2 remained present after the initial spike. A correlation of mitoPO2 with mean arterial pressure (MAP) and arterial partial oxygen pressure measured by CIRD (CIRD-PaO2) seemed not present. One of the experimental pigs survived.Conclusions: This experimental pilot study shows that continuous measurements of skin mitoPO2 in pigs treated with ECPR are feasible. The delay in initial mitoPO2 and discrepancy of mitoPO2 and MAP in our small sample study could point to the possible value of additional measurements besides MAP to monitor the quality of tissue perfusion during cardiac arrest and ECPR.

Bioenergy production from the organic fraction of municipal solid waste and sewage sludge using mesophilic anaerobic co-digestion: An experimental and kinetic modeling study

Following the rapid surge in global demand for energy as well as the rising generation of municipal solid waste (MSW) worldwide, much more attention has been drawn to sustainable waste management solutions to tackle both problems. The present study investigated the potential for biogas production from the anaerobic co-digestion (ACD) of the organic fraction of MSW (OFMSW) and sewage sludge after physical and chemical pretreatments at three inoculum-to-substrate (I/S) ratios (ISR: 2, 4, & 6) and three levels of total solids (TS: 3, 5, & 7%). A series of experiments were further carried out in laboratory-scale (1-L) single-stage digesters in batch mode at the temperature of 35 °C (viz. Under mesophilic conditions) for 50 days. The results demonstrated that the digestion produced the best outputs at TS = 5% and ISR = 2, whereby it offered the biogas yield of 0.697, the methane (CH4) production of 0.448 m3/Kg-volatile solid (VS)added, and the total VS (TVS) removal by 65%. Moreover, it was observed that most reactors with TS = 7% encountered the phase separation problem while augmenting the TS content from 3 to 5% increased the biogas yield and CH4 production. The kinetic study of the mesophilic ACD additionally showed that both models of modified Gompertz (GM) equation and logistic function (LF) provided a reasonably accurate description of biogas production, but the first-order (FO) model failed in this task. Furthermore, the amount of sludge (namely, ISR) in the digester enlarged and the models showed a better fit to the experimental data.

Effect of Intraparticle Mass Transfer on the Catalytic Site Formation in the Preparation of Silica‐Supported Metallocene Catalysts

AbstractThe preparation conditions of silica‐supported metallocene catalysts impact the catalytic performance and consistency in ethylene polymerization. In a commonly used catalyst impregnation technique, the concentrations of catalyst solutions and the contact time between silica microparticles and catalyst solutions are used to ensure uniform and stable immobilization of coactivator methyl aluminoxane (MAO) and metallocenes. The overall catalytic activities for olefin polymerization, catalyst particle fragmentation, and the resulting polymer particle morphology depend upon the distribution of active catalyst sites within the silica catalyst particle. This work presents both experimental and theoretical modeling studies on the intraparticle spatial distribution of MAO and metallocene in highly porous silica microparticles for ethylene polymerization in a liquid‐slurry phase. The silica‐catalyst solution contact times and the catalyst solution concentrations are used as two major variables to vary the intraparticle catalyst site distributions. The overall aluminum and zirconium contents in the catalyst and their radial distributions are observed to be strongly affected by the impregnation conditions. A mathematical model is also derived for the catalyst impregnation process and it provides adequate predictions of the impregnation process characteristics.

A Modelling Approach for the Analysis of Underwater Explosive Performance Trials

AbstractWe present here a coupled experimental and numerical modelling study to compare the underwater performance of different explosive charge types in simple geometries with a view to having confidence in the use of these models in the design of more complex warheads. Numerical modelling is used to predict the shock and bubble performance of underwater detonated charges and is intended to be used for comparison of the performance of different charge compositions. Model predictions are compared to experimental data from the underwater detonation of 1 kg cylindrical charges. It is shown that a simple 1D spherical geometry Eulerian hydrocode solution is suitable for comparison of the performance of different charge types provided that gauges are located on the radial axis of the charge and located a sufficient distance from the charge. Predictions using our chosen explosive models are shown to accurately capture the shock and bubble performance of ideal and non‐ideal charges tested and the effects of charge casing so that these models can be used in more complex warhead design studies at a later date.

Pairing Experimental and Mathematical Modeling Studies on Fluidized Beds for Enhancement of Models Predictive Quality: A Current Status Overview

Modeling of gas-solid fluidized systems has been a prevailing challenge over the last few decades. With different approaches and implementing different sub-models to capture the essential multiphase and multiscale phenomena in these systems, major advances have been achieved, even though most models are only subject to a practical validation of macroscopic parameters. The current description of fluidized beds through mathematical models relies on the inclusion of vast sub-models, leading to an unquantifiable degree of uncertainty on the models’ applicability for extrapolation studies. Furthermore, each closure and fitting parameter in the model represents a possible source of deviation, and their optimization, hence, becomes another major challenge. The recent advances in measurement techniques can enable us to troubleshoot and optimize the implemented models and sub-models based on local scale measurements. Local multiphase hydrodynamic information obtained by advanced measurement techniques can enable the validation of local predictions and optimization of the coupled sub-models, leading to the development of simplified and highly predictive models. Thus, pairing advanced experimental studies on these systems with insightful modeling approaches is required to advance the shortcoming and enhance the predictive quality of the models. In this work, an overview of the status of modeling and experimental measurement techniques for gas-solid fluidized beds is presented; then, an overview on pairing both experimental and modeling studies to improve the models’ local predictions for fluidized beds is presented.

Time-dependent reliability analysis of fixed offshore structures under stochastic loadings

Fixed offshore structures under stochastic loadings usually have time-dependent reliability due to time-varying statistics of nonstationary load effects. Since closed-form solutions for such time-varying statistics are difficult to obtain, traditional methods cannot analytically evaluate reliability of structures. In this paper: (1) the explicit closed-form solutions for variances of nonstationary load effects at arbitrary time of linear structures are derived by a pole-residue method; and (2) the explicit solution of a time-dependent reliability index of the structure is then established. For computing displacement variances of offshore structures to waves using the pole-residue method in step (1), an innovative approach of writing the wave force power spectral density into its pole-residue form is developed. To verify the efficiency of the proposed method, a numerical example studies the time-dependent reliability index of the monopile foundation of offshore wind turbines under random waves. Furthermore, a hybrid numerical–experimental study of a jacket platform model to ground motions is conducted. The results indicate that reliability of structures at the nonstationary part is significantly smaller than that at the stationary part. This study provides a reference and advocates attention to structural failures generated by nonstationary responses to extreme loads, e.g., earthquakes.

A new phenothiazine derivate is active against Clostridioides difficile and shows low cytotoxicity.

The rapid evolution of antibiotic resistance in Clostridioides difficile and the consequent effects on prevention and treatment of C. difficile infections (CDIs) are matters of concern for public health. Thioridazine, a compound belonging to the phenothiazine group, has previous shown antimicrobial activity against C. difficile. The purpose of this present study was to investigate the potential of a novel phenothiazine derivative, JBC 1847, as an oral antimicrobial for treatment of intestinal pathogens and CDIs. The minimal inhibition concentration and the minimum bactericidal concentration of JBC 1847 against C. difficile ATCC 43255 were determined 4 μg/mL and high tolerance after oral administration in mice was observed (up to 100 mg/kg bodyweight). Pharmacokinetic modeling was conducted in silico using GastroPlusTM, predicting low (< 10%) systemic uptake after oral exposure and corresponding low Cmax in plasma. Impact on the intestinal bacterial composition after four days of treatment was determined by 16s rRNA MiSeq sequencing and revealed only minor impact on the microbiota in non-clinically affected mice, and there was no difference between colony-forming unit (CFU)/gram fecal material between JBC 1847 and placebo treated mice. The cytotoxicity of the compound was assessed in Caco-2 cell-line assays, in which indication of toxicity was not observed in concentrations up to seven times the minimal bactericidal concentration. In conclusion, the novel phenothiazine derivative demonstrated high antimicrobial activity against C. difficile, had low predicted gastrointestinal absorption, low intestinal (in vitro) cytotoxicity, and only induced minor changes of the healthy microbiota, altogether supporting that JBC 1847 could represent a novel antimicrobial candidate. The clinical importance hereof calls for future experimental studies in CDI models.

Research on the impact coefficient of vehicle wheel load on bridge expansion joint by scale model experiment

The wheel load of the vehicle acting on the bridge expansion joint is a kind of dynamic load, and its impact coefficient needs to be determined, so as to provide basic design parameters for the bridge expansion joint. In this paper, the scale model of the bridge and the vehicle is designed and constructed, and the experimental study of vehicle model passing through bridge model is carried out. In the experiment, the wheel impact load of the vehicle on the bridge expansion joint is measured, and the impact coefficient of the wheel load is calculated. The measured results show that the greater the vehicle speed, the greater the impact load of the wheel on the expansion joint, that is, the greater the impact coefficient. The larger the width of the gap in the expansion joint, the greater the impact load and impact coefficient of the wheel on the expansion joint. The greater the mass of the vehicle, the longer the contact length between the wheel and the road surface, which reduces the impact effect and the impact coefficient of the wheel load on the expansion joint. The maximum impact coefficient of wheel load is greater than the design value in the Chinese bridge code, i.e. 0.45, even greater than that in the American bridge code, i.e. 0.75.

RISPERIDONE-INDUCED MODERATE CENTRAL HYPOTHERMIA

TOPIC: Critical Care TYPE: Medical Student/Resident Case Reports INTRODUCTION: Risperidone is a second-generation atypical antipsychotic medication (APD) commonly used to treat schizophrenia and bipolar disorder. An infrequent dangerous side effect of APDs is hypothermia, defined as a core body temperature < 35 Celsius (C) [1]. CASE PRESENTATION: A 61-year-old male with hypertension, epilepsy, and schizophrenia was transferred to the emergency department for bilateral lower extremity weakness and slow speech for two days. Medications included carbamazepine and risperidone. He denied being outside in the cold and stated he has a heater at home. A week prior, at a follow-up with his primary physician, his oral temperature was 35.5C. A clinical exam revealed dysphasia and right lower leg weakness. Core rectal temperature was 29.1C, indicating moderate hypothermia. Computed tomography of the head and neck with contrast displayed no acute intracranial abnormality. Blood work revealed a normal thyroid-stimulating hormone, cardiac enzymes, and lactic acid. Urinalysis was negative for infection. Chest x-ray showed no acute abnormalities. Carbamazepine level was in the therapeutic range. In the intensive care unit, he was given warmed intravenous fluids and placed on an external warmer with constant temperature monitoring. Due to central hypothermia concerns, risperidone was held, and external warming was applied. Gradually, core temperature increased to 36.5C over the next 14 hours. He had no signs of infection or metabolic derangements to increase his hypothermia risk. He improved quickly and was downgraded to the medical floor. DISCUSSION: Experimental animal model studies reveal a dose-dependent decline in temperature with risperidone [2]. The exact incidence is higher than reported medical literature based on reports submitted to Food and Drug Administration. Mild hypothermia was common and moderate hypothermia was rare after few years of therapy [3]. Mild hypothermia symptoms are inconspicuous and odd, like apathy, confusion, shivering, or hunger, and are often missed [1]. Clinical thermometers fail to register a temperature < than 34.4C. The risk is more in men and patients with schizophrenia and bipolar disorder. Risk factors such as age > 70 years, other APDs, and organic diseases amplify it [3]. APDs are highly antagonistic at serotonin receptors (5-HT2a) than dopamine (D2) and a2 adrenergic receptors. 5-HT2a and a2 receptors act to increase core temperature while D2 acts to decrease it [3]. APD use leads to an imbalance promoting lower core temperature. Monitoring temperature is essential at APDs initiation and dosage changes. Consideration of other medical comorbidities is a must. CONCLUSIONS: APDs induced moderate central hypothermia is a rare, reversible cause. Failure to recognize it by critical care providers can be fatal. REFERENCE #1: Polderman KH. Mechanisms of action, physiological effects, and complications of hypothermia. Crit Care Med. 2009;37(7 Suppl):S186-202 REFERENCE #2: Oerther S, Ahlenius S. Atypical antipsychotics and dopamine D(1) receptor agonism: an in vivo experimental study using core temperature measurements in the rat. J Pharmacol Exp Ther. 2000;292(2):731-736. REFERENCE #3: : Szota AM, Araszkiewicz AS. The risk factors, frequency and diagnosis of atypical antipsychotic drug-induced hypothermia: practical advice for doctors. Int Clin Psychopharmacol. 2019;34(1):1-8. DISCLOSURES: No relevant relationships by Dennis Chairman, source=Web Response No relevant relationships by Sahithi Katragadda, source=Web Response No relevant relationships by Parth Patel, source=Web Response No relevant relationships by Tarang Patel, source=Web Response No relevant relationships by SACHIN PATIL, source=Web Response

Experimental and numerical modeling study of rock joint mechanical properties and failure mechanisms under cyclic shear

Cyclic loading is a common concept in geotechnical engineering, which has an important effect on rock joints. To study the mechanical properties and failure mechanisms of rock joints under cyclic loading, a kind of rock joint cyclic shear device with a top-to-top configuration is proposed in this work. Cyclic shear tests of rock joints are carried out with the cyclic shear equipment. With three–dimensional texture scanning technology, the cyclic shear failure mode of the rock joint is analyzed. The variation trends of shear strength and stiffness of the rock joint under the combined action of normal stress, joint roughness, shear rate, and cyclic shear number are studied. The results show that the normal stress and the roughness are positively related to the cyclic shear strength of the rock joint. With the increase of shear rate and number of cycles, the shear strength and stiffness of the rock joints decrease gradually. In the first cycle of the shear process, the peak shear strength and stiffness of the rock joints reach the maximum values. After the second cycle, the peak shear strength and stiffness of the rock joints decrease slightly and tend toward a constant value under the same normal stress. Observation of the sheared rock joint surface reveals that sliding and shearing damage to the protrusions occurred during the cyclic shear process. Under the combined action of the normal stress, joint roughness, shear rate, and cyclic shear number, the protrusions would slide while moving up to a different height until they are eventually sheared off. In the next cyclic shear process, the friction and shear damage of the residual protrusions continues to occur. With the increase of the number of cyclic shear processes, the wear on the residual protrusions gradually decreases and stabilizes. Finally, the numerical cyclic shear test of the rock joint is performed with the discrete element method (DEM) code 3DEC. A good comparison is found between laboratory data and DEM results.

An experimental and kinetic modeling study of NOx sensitization on methane autoignition and oxidation

An experimental and kinetic modeling study of the influence of NOx (i.e. NO2, NO and N2O) addition on the ignition behavior of methane/‘air’ mixtures is performed. Ignition delay time measurements are taken in a rapid compression machine (RCM) and in a shock tube (ST) at temperatures and pressures ranging from 900–1500 K and 1.5–3.0 MPa, respectively for equivalence ratios of 0.5–2.0 in ‘air’. The conditions chosen are relevant to spark ignition and homogeneous charge compression ignition engine operating conditions where exhaust gas recirculation can potentially add NOx to the premixed charge. The RCM measurements show that the addition of 200 ppm NO2 to the stoichiometric CH4/oxidizer mixture results in a factor of three increase in reactivity compared to the baseline case without NOx for temperatures in the range 600–1000 K. However, adding up to 1000 ppm N2O does not show any appreciable effect on the measurements. The promoting effect of NO2 was found to increase with temperature in the range 950–1150 K, while the sensitization effect decreases at higher pressures. The experimental results measured are simulated using NUIGMech1.2 comprising an updated NOx sub-chemistry in this work. A kinetic analysis indicates that the competition between the reactions ĊH3 + NO2 ↔ CH3Ȯ + NO and ĊH3 + NO2 (+M) ↔ CH3NO2 (+M), the former being a propagation reaction and the latter being a termination reaction governs NOx sensitization on CH4 ignition. Recent calculations by Matsugi and Shiina (A. Matsugi, H. Shiina, J. Phys. Chem. A. 121 (2017) 4218–4224) for the nitromethane formation reaction CH3 + NO2 (+M) ↔ CH3NO2 (+M), together with the recently calculated rate constants for HONO/HNO2 reactions significantly improve ignition delay time predictions in the temperature range 600–1000 K. Furthermore, the experiments with NO addition reveal a non-monotonous sensitization impact on CH4 ignition at lower temperatures with NO initially acting as an inhibitor at low NO concentrations and then as a promoter as NO concentrations increase in the mixture. This non-monotonous trend is attributed to the role of the chain-termination reaction ĊH3 + NO2 (+M) ↔ CH3NO2 (+M) and the impact of NO on the transition to the chain-branching steps CH2O + HȮ2 ↔ HĊO + H2O2, H2O2 (+M) ↔ ȮH + ȮH (+M), HĊO ↔ CO + Ḣ followed by CO + O2 ↔ CO2 + Ö and Ḣ + O2 ↔ Ö + ȮH. NUIGMech1.2 is systematically validated against the new ignition delay measurements taken here together with species measurements and high temperature ignition delay time data available in the literature for CH4/oxidizer mixtures diluted with NO2/N2O/NO and is observed to accurately capture the sensitization trends.

Direct measurement of rate-dependent mode I and mode II traction-separation laws for cohesive zone modeling of laminated glass

This paper reports a combined experimental-modeling study on the adhesion at glass/poly(vinyl butyral) (PVB) interfaces. PVB is a critical component in laminated glasses that provides impact resistance and prevents spallation in the event of glass breakage. We characterize the mode I (normal) and mode II (shear) interfacial fracture behaviors in glass/PVB/glass laminates and obtained independent cohesive (traction–separation) laws for the two modes. We observe a pronounced rate dependence of both traction-separation laws. Specifically, with increasing loading rate, the interfacial stiffness, the peak stress, and the fracture toughness increase while the critical opening or shear displacement decreases. These measured traction-separation laws are used as inputs in finite element analysis to predict the mechanical behavior of the peel test, which agrees reasonably well with the experimental results. Finite element analysis of a glass laminate subjected to impact loading demonstrates how the measured interfacial properties can be used to predict the mechanical behavior and failure of laminated glass.

Computational modeling of axial rotation for the evolution of temperature in horizontal toroidal cans under pasteurization conditions

Axial rotation mechanism has been widely used during thermal processing of liquid containing cans. Besides this can geometry modification might be an innovative approach to increase heat transfer rates. Therefore, the objective of this study was to determine temperature distribution and effect of rotation rate in axially rotating toroidal cans. For this purpose, experimental and numerical modeling studies were carried out. In the experimental studies, toroidal cans including distilled water were processed in hot water, and temperature data were used for computational model validation and mesh independency. Then, the second set of simulations were conducted to determine the rotational effects on temperature evolution. Effects of gravitational buoyancy, centrifugal and Coriolis forces were determined, and Coriolis forces increased up to 4 times with increased rotation rates (20–160 rpm). With this aspect, process time for 70 °C increase was reduced by ≈40 and 33.3% at 80 and 160 rpm compared to conventinal cylindrical cans. This study is an introduction to modify can geometry and process parameters to reduce quality losses and decrease energy use. However, industrial practice has still significant challenge for manufacturing and using in the process line.

Local Effects of a 1940 nm Thulium-Doped Fiber Laser and a 1470 nm Diode Laser on the Pulmonary Parenchyma: An Experimental Study in a Pig Model.

The lungs are a common site of metastases from malignant tumors. Their removal with a minimal but safe tissue margin is essential for the long-term survival of patients. The aim of this study was to evaluate the usefulness of a 1940 nm thulium-doped fiber laser (TDFL) and a 1470 nm diode laser (DL) in a pig model of lung surgery that involved the incision and excision of lung tissue. Histopathological analysis was performed on days 0 and 7 after surgery. Neither TDFL nor DL caused significant perioperative or postoperative bleeding. Histological analysis revealed the presence of carbonized necrotic tissue, mixed fibrin–cellular exudate in the superficial zone of thermal damage and bands of deeper thermal changes. The mean total width of thermal damage on day 0 was 499.46 ± 61.44 and 937.39 ± 109.65 µm for TDFL and DL, respectively. On day 7, cell activation and repair processes were visible. The total width of thermal damage was 2615.74 ± 487.17 µm for TDFL vs. 6500.34 ±1118.02 µm for DL. The superficial zone of thermal damage was narrower for TDFL on both days 0 and 7. The results confirm the effectiveness of both types of laser in cutting and providing hemostasis in the lungs. TDFL caused less thermal damage to the lung parenchyma than DL.

What Is the Role of GABA Transporters in Seizures?

The brain utilizes γ‐aminobutyric acid (GABA) as its primary inhibitory neurotransmitter to control neuronal excitability and modulate the ongoing activity of neuronal ensembles. GABA controls the generation of membrane potential oscillations, which provide the time window for integration of synaptic inputs and generation of activity patterns in neuronal networks. These effects require a fine control of GABAA and GABAB receptor activation, which, in turn, depends on both the precise timing of GABA release from presynaptic terminals and GABA clearance from the extracellular space. GABA is synthesized in presynaptic terminals from glutamate via the glutamic acid decarboxylases 65 and 67 and is incorporated in synaptic vesicles via the vesicular GABA transporter, referred to as vesicular inhibitory amino-acid transporter (VIAAT) as it also mediates vesicular uptake of glycine1 (Figure). The clearance of GABA after release depends on its uptake by specific GABA transporters (GATs), including GAT-1, expressed predominantly in axons and presynaptic terminals, and GAT-3, expressed primarily in astrocytes.2,3 By controlling extracellular GABA levels, GATs have a major role in regulating tonic and phasic inhibition in the cerebral cortex, hippocampus, thalamus, and other areas.2,3 Experimental studies in mouse models indicate a major role of GATs in regulating cortical excitability and predisposition to seizures. Mutations affecting the GABA transporters have been linked to different seizure phenotypes. For example, loss of function mutations of the SLC6A1 gene encoding GAT-1 have been associated with epilepsy with myoclonic-atonic seizures and with absence seizures.4,5

Experimental and kinetic modeling studies of polyoxymethylene dimethyl ether (PODE) pyrolysis in jet stirred reactor

Polyoxymethylene dimethyl ethers (DMMn) is regarded as a potential alternative fuel for transportation utilization. The jet stirred reactor (JSR) pyrolysis of DMM1−3 was studied at temperatures of 450∼1080 K and pressures of 1.03 atm with the residence time (τ) of 2 s. A gas chromatography/mass spectrometry (GC–MS/FID) was used to detect and provide reliable pyrolysis experimental data. Seven key pyrolysis products were detected and measured in the present work, including fuel, methyl formate, methanol, acetaldehyde, methane, ethane and ethylene. A detailed kinetic model of DMM1−3 pyrolysis was elaborated. Both rate of production (ROP) and sensitivity analysis were performed to reveal the DMM1−3 pyrolysis processes. Results show that the chemical kinetic simulation can reproduce the consumption of fuel and most intermediate species reasonably well. With the increase of n from 1 to 3 inside DMM1−3, the reactivity increases evidently and the initial pyrolysis temperature decreases significantly, which is mainly resulted from different fuel-specific chain initiation reactions of DMM1−3. Methane and methyl formate are two detected key species with relatively significant concentrations. It was revealed that the fuel-specific chain initiation reactions of DMM1−3 can also significantly affect the production and consumption paths of methyl formate. In addition to the major production and consumption paths of formaldehyde, two key competitive channels were found to perform relatively high negative sensitivity to formaldehyde production of DMM2 and DMM3.

Experimental and kinetic modeling study of n-pentane oxidation at 10 atm, Detection of complex low-temperature products by Q-Exactive Orbitrap

Renewable feedstock such as biomass derivatives (hemicellulose, furfural) can be used to produce synthetic fuels, e.g., n-pentane, of interest for enhancing performance of diesel and gasoline engines. Whereas numerous studies of n-pentane have been published, its low temperature oxidation is not fully characterized and even recent kinetic models do not incorporate extended oxidation pathways which still need to be observed for n-pentane. In this context, a continuous flow fused-silica jet-stirred reactor (JSR) was used for studying the oxidation of 2500 ppm of n-pentane at 520‒800 K, 10 atm (representative of piston engines operating conditions), an equivalence ratio of 0.5, and a residence time of 1.5 s. Oxidation products were analyzed in the gas phase using gas chromatography (thermal conductivity, TCD and flame ionization, FID), Fourier-transform infrared spectrometry (FTIR), and electron impact ionization-quadrupole mass spectrometry (EI-qMS). Gaseous products were also dissolved in acetonitrile for characterization using flow injection analysis (FIA), high-pressure and ultra-high-pressure liquid chromatography (HPLC and UHPLC) coupled to atmospheric pressure chemical ionization (APCI) and Q-Exactive®-Orbitrap high resolution mass spectrometry (HRMS). This allowed detecting lower and higher mass oxygenated molecules such as methyl vinyl ketone (MVK) and 2,5-dihydrofuran (C4H6O), 2-butanone (C4H8O), 3-pentene-2-one (C5H8O), pentanediones (C5H8O2), cyclic ethers and pentanones (C5H10O), C3‒C5 alkylhydroperoxides (C3H8O2, C4H10O2, C5H12O2), C2‒C5 alkenylhydroperoxides (C2H4O2, C3H6O2, C4H8O2, C5H10O2), C3‒C5 keto-hydroperoxides (C3H6O3, C4H8O3, C5H10O3), and highly oxygenated molecules (C5H8O4, C5H12O4, C5H10O4, C5H10O5, C5H10O7) produced through multiply O2 addition on fuel's radicals and internal H-shifts. Among these products 15 had not been reported before. Simulation of the present experiments showed discrepancies between experimental results and predictions.