Propylene Research Articles

Axially Chiral N‐Oxide Catalysts for the Allylation and Crotylation of Aromatic Aldehydes: Exploiting Nonlinear Effects

A new family of IAN‐type amine N‐oxides is presented as catalysts for the allylation and crotylation of aromatic aldehydes with allyltrichlorosilanes. The catalyst design anticipates the formation of dimers, which translates into a remarkably positive nonlinear effect in the allylation reaction. This nonlinear effect enables utilization of the catalyst in its subenantiopure form. As enantiopure catalysts are not required under this regime, the synthesis of these N‐oxides is straightforward through asymmetric synthesis, avoiding lenghty synthesis from the chiral pool or resolution of diastereoisomers. Studies of the corresponding crotylation with Z‐ and E‐crotylsilanes suggest that the reaction proceeds through a chair‐like transition state

Smart LPG Regulator

The Smart LPG Regulator is designed to oversee the regulation of pressurized steel gas cylinders in residential households. The primary goal of this project is to prevent the potential risks associated with LPG gas leaks, including the loss of life, injuries, and health concerns. The system is equipped to identify gas leaks and issue auditory and visual alerts through a buzzer, a display, and a servo motor, which promptly closes the gas cylinder regulator to terminate the gas supply. The LPG Gas Detector (MQ6) is a suitable sensor with high sensitivity to Liquid Petroleum Gas (LPG), including propane, proficient, isobutene, and natural gas. It is also capable of detecting easily flammable gases, mainly methane. Data collected by the MQ6 sensor is processed by the Atmega 328P microcontroller and presented through the output components. The LCD screen will display 'GAS LEAK,' the buzzer will sound an alarm, and the servo motor will continue to close the regulator valve on the gas cylinder. The MQ6 sensor can identify gas leaks from the gas cylinder, gas pipes, or kitchen stove burners. One significant advantage of this system is its ability to shut off the gas cylinder supply, indirectly preventing accidents and injuries. The system's design is tailored to accommodate the standard size of gas cylinders used in residential homes, with domestic consumers as the target user group.

Flame propagation behavior inside a closed duct upstream of a flame arrester housing

A possible way to introduce hydrogen into the energy matrix would be to enrich traditional fuels like natural gas and propane with hydrogen. Therefore, the study of the flame propagation behavior of these hydrogen enriched fuels becomes important to future industrial applications. In the present work the aim was to experimentally study the effect of hydrogen enrichment of propane and natural gas. However, in order to achieve more generality, the studied mixtures were characterized through the Lewis (Le), Zeldovich (Ze) and the reaction Damköler (Da°) numbers. A total of six mixtures were considered, in which the Ze varied from 4.94 to 8.45, the Le varied from 0.71 to 1.36 and the Da° varied from 14.56 to 36.11. In addition, the obtained results were compared to previous work to assess the effect of the experimental boundary conditions on the flame propagation velocity. The experimental results show that, for mixtures with similar Le numbers, the lower the Ze number the higher the flame propagation velocity. The maximum propagation velocities obtained in the first propagation section of the module are between 18.60 m/s and 57.11 m/s. Therefore, these flames can be considered as weakly accelerating flames. Moreover, the maximum flame propagation velocities showed a good correlation with the product Le × Ze. Regarding the presence of the flame arrester housing without an arrester element, it was observed that it causes an increase in flame propagation velocity. However, when compared to a previous work in which a flame arrester element was inside the housing, the velocity was higher for the present work.

Toxicity mechanism of acrolein on energy metabolism disorder and apoptosis in human ovarian granulosa cells

Acrolein (ACR), an unsaturated, highly reactive aldehyde, is a widespread environmental toxin. ACR exerts permanent and irreversible side effects on ovarian functions. Granulosa cells play a crucial role in supporting ovarian function. Thus, in this study, we investigated the toxicity effects of granulosa cells induced by ACR. Following treatment with varying ACR concentrations (0, 12.5, 25, 50, and 100 μM), we observed that ACR exposure induced reactive oxygen species accumulation, mitochondrial energy metabolism disorder, and apoptosis in KGN cells (a human ovarian granulosa cell line) in a dose-dependent manner. In addition, mitochondrial biogenesis in KGN cells displayed biphasic changes after ACR exposure, with activation at a low ACR dose (12.5 μM), but inhibition at higher ACR doses (≥50 μM). SIRT1/PGC-1α-mediated mitochondrial biogenesis is crucial for maintaining intracellular mitochondrial homeostasis and cellular function. The inhibition/activation of the SIRT1/PGC-1α pathway in KGN cells validated its role in ACR-induced damage. The results indicated that the inhibition of the SIRT1/PGC-1α pathway aggravated ACR-induced cell damage, whereas its activation partially counteracted ACR-induced cell damage. This study attempted to uncover a novel mechanism of ACR-induced ovarian toxicity so as to provide an effective treatment option for safeguarding female reproductive health from the adverse effects of ACR.

Visualization of Acrolein Upregulation during Ferroptosis by a Ratiometric Fluorescent Probe.

Ferroptosis is a pattern of cell death caused by iron-dependent accumulation of lipid peroxides and is closely associated with the occurrence and development of multiple diseases. Acrolein (ACR), one of the final metabolites of lipid peroxidation, is a reactive carbonyl species with strong biotoxicity. Effective detection of ACR is important for understanding its role in the progression of ferroptosis and studying the specific mechanisms of ferroptosis-mediated diseases. However, visualization detection of ACR during ferroptosis has not yet been reported. In this work, the first ratiometric fluorescent probe (HBT-SH) based on 2-(2'-hydroxyphenyl) benzothiazole (HBT) was designed for tracing endogenous ACR with an unprecedented regiospecific ACR-induced intramolecular cyclization strategy, which employs 2-aminoethanethiol as an ACR-selective recognition receptor. The experimental results showed that HBT-SH has excellent selectivity, high sensitivity (LOD = 0.26 μM) and good biocompatibility. More importantly, the upregulation of ACR levels was observed during ferroptosis in HeLa cells and zebrafish, indicating that ACR may be a specific active molecule that plays an essential biological role during ferroptosis or may serve as a potential marker of ferroptosis, which has great significance for studying the pathological process and treatment options of ferroptosis-related diseases.

Theanine Capture of Reactive Carbonyl Species in Humans after Consuming Theanine Capsules or Green Tea.

Acrolein (ACR), methylglyoxal (MGO), and glyoxal (GO) are a class of reactive carbonyl species (RCS), which play a crucial role in the pathogenesis of chronic and age-related diseases. Here, we explored a new RCS inhibitor (theanine, THE) and investigated its capture capacity on RCS in vivo by human experiments. After proving that theanine could efficiently capture ACR instead of MGO/GO by forming adducts under simulated physiological conditions, we further detected the ACR/MGO/GO adducts of theanine in the human urine samples after consumption of theanine capsules (200 and 400 mg) or green tea (4 cups, containing 200 mg of theanine) by using ultraperformance liquid chromatography-time-of-flight-high-resolution mass spectrometry. Quantitative assays revealed that THE-ACR, THE-2ACR-1, THE-MGO, and THE-GO were formed in a dose-dependent manner in the theanine capsule groups; the maximum value of the adducts of theanine was also tested. Furthermore, besides the RCS adducts of theanine, the RCS adducts of catechins could also be detected in the drinking tea group. Whereas, metabolite profile analysis showed that theanine could better capture RCS produced in the renal metabolic pathway than catechins. Our findings indicated that theanine could reduce RCS in the body in two ways: as a pure component or contained in tea leaves.

Heat integration analysis based on recycle split vapor ethane recovery process

AbstractRecovering ethane from natural gas involves significant energy consumption. Globally, the recycle split vapor process (RSV) is widely adopted as an efficient method for ethane recovery. Nonetheless, one major challenge faced by the RSV process is the lack of adequate heat integration, despite its overall effectiveness. In this article, we investigate the heat integration of the RSV process and propose two novel ethane recovery processes: the recycle split vapor process with direct heat integration of the feed gas (RSV‐DTI) and the recycle split vapor process with split heat integration of the feed gas (RSV‐SHI). A comparative analysis is conducted among these three processes, focusing on integrated energy consumption, exergy efficiency, and economic investment. The study's findings reveal the following: (1) The RSV‐DTI process distinguishes itself with its reduced energy consumption, enhanced stability, and minimized refrigerant usage. In comparison to the RSV process, the RSV‐DTI process achieves a reduction of over 15% in total compression duty and a remarkable decrease of 68% in propane usage. (2) Electricity emerges as the predominant energy consumed in the ethane recovery process, and the RSV‐DTI process significantly improves upon this aspect. Notably, the RSV‐DTI process incurs the lowest investment cost, yielding a swift payback period of approximately 1 year for the plant. The characteristics of the RSV‐DTI process are investigated, and the effect of changes in feed gas conditions on the heat integration of the RSV‐DTI process is analyzed. The characteristics of the RSV‐DTI process show the following: (1) Different pressures of feed gas existing in the main cold box have different minimum heat integration temperatures (MHIT). When the feed gas temperature is lower than the MHIT, heat integration becomes difficult, and the heat energy can be supplied by hot liquid propane at 48°C. When the feed gas temperature is higher than the MHIT, changes in feed gas temperature have little effect on the process, only affecting the external gas temperature. (2) The heat transfer duty of the demethanizer sideline outlet stream is affected by the feed gas pressure. To enhance heat integration, it is recommended to set the heat transfer duty of the low‐temperature sideline outlet stream (DLTSS) between 40% and 90% of the reboiler duty and the heat transfer duty of the high‐temperature sideline outlet stream (DHTSS) between 40% and 75% of the reboiler duty.

Radical Allylation of Aldehydes with Allenes by Photoredox Cobalt and Chromium Dual Catalysis

AbstractA dual cobalt and chromium photoredox-catalyzed allylation of aldehydes with allenes through a photo metal-hydride atom transfer (MHAT) process has been developed to yield homoallylic alcohols with exceptional diastereoselective control. This sustainable and efficient method holds significant promise for applications in the synthesis of valuable organic compounds.

Oxylipin biosynthesis via an unprecedented 16-hydroperoxide lyase pathway in green tissues of cucumber (Cucumis sativus L.) plants

The plant lipoxygenase cascade is a source of various regulatory oxylipins that play a role in cell signalling, stress adaptation, and immune response. Recently, we detected an unprecedented 16(S)-lipoxygenase, CsLOX3, in the leaves and fruit pericarp of cucumber (Cucumis sativus L.). In the present work, an array of products biosynthesized through the conversions of α-linolenic acid 16-hydroperoxide (16-HPOT) was detected. Firstly, a prominent 15-hydroxy-9,12-pentadecadienoic acid (Me/TMS) was detected, the product of hydroperoxide lyase (HPL) chain cleavage of 16-HPOT and further reduction of aldehyde 15-oxo-9,12-pentadecadienoic acid to alcohol. Besides, the presence of dicarboxylic acid, 3,6-pentadecadiene-1,15-dioic acid, was deduced from the detection of its catalytic hydrogenation product, pentadecane-1,15-dioic acid. Finally, 12,15-dihydroxypentadecanoic acid (Me/TMS) was detected amongst the hydrogenated products, thus indicating the presence of the parent 12,15-dihydroxy-9,13-pentadecadienoic acid. To confirm the proposed HPL chain cleavage, the 16(S)-HPOT was prepared and incubated with the recombinant cucumber HPL CYP74B6 enzyme. The CYP74B6 possessed high activity towards 16-HPOT. Chain cleavage yields the (9Z,12Z)-15-oxo-9,12-pentadecadienoic acid, undergoing a spontaneous isomerization into (9Z,13E)-15-oxo-9,13-pentadecadienoic acid. Thus, the cucumber plants as well as the recombinant cucumber HPL CYP74B6 possessed unprecedented 16-HPL activity, cleaving 16-HPOT into a C15 fragment, 15-oxo-9,12-pentadecadienoic acid, and a complementary volatile C3 fragment, propionic aldehyde. The 16-LOX/16-HPL route of oxylipin biosynthesis presents a novel facet of the plant LOX pathway.

Recycled mask polypropylene microfibers benefit tensile properties and prevent thermally induced spalling of high-strength engineered cementitious composite (HS-ECC)

The COVID-19 pandemic has led to a significant amount of waste medical masks being generated, which if not properly managed would pose a substantial risk to the natural environment. In this context, this study focuses on upcycling the waste medical mask propylene (PP) microfibers in high-strength engineered cementitious composites (HS-ECC) to mitigate its explosive spalling issue upon fire exposure. At ambient temperature, the compressive strength of Ref-ECC (without PP microfibers) reached 96.4 MPa, and the incorporation of recycled mask fibers (RMFs) up to 0.5 vol% had a negligible effect on it. The incorporation of low-cost RMFs benefited the uniaxial tensile properties of HS-ECC. For instance, at 25 °C, the incorporation of 0.5 vol% RMFs increased the tensile strain capacity and tensile strength of the HS-ECC to 2.60% and 7.9 MPa, from those of the Ref-ECC (2.03% and 7.1 MPa), respectively. The 0.5 vol% RMFs in the HS-ECC increased the tensile strain capacity to 3.80% at 60 °C, 4.50% at 90 °C and 5.23% at 120 °C notwithstanding their reduced tensile strength, respectively. The RMFs in the HS-ECC induced inner (sub)micron-sized cracks after thermal exposures, facilitating multi-cracking behavior. After 600 °C/2h heating, severe spalling occurred in the Ref-ECC cylinder specimens, demonstrating that polyethylene (PE) fibers alone (at 1.8 vol%) cannot prevent spalling upon fire exposure. However, the incorporation of RMFs (as little as 0.3 vol%) was proven as an effective preventive measure against the explosive spalling phenomenon in HS-ECC.

Novel strategy to regulate the geometric and electronic structure of Pt catalyst for efficient propane combustion

The geometric and electronic structure of Pt active sites plays a crucial role in determining the catalysts performance, but precise regulation remains challenging. Herein, we propose a novel approach to modulate the nature of Pt active sites by combining photo-deposition of Pt nanoparticles with ultra-low Mo loading (0.1 wt%) modification on Pt/SiO2 catalysts. The addition of ultra-low loading Mo promoter not only effectively reduces the size of Pt particles but also donates electrons to the Pt particles. Furthermore, the photo-deposited Pt particles exhibit a higher proportion of metallic Pt species, which is more stable than that metallic Pt species obtained by H2 reduction, compared to those prepared using traditional wetness impregnation methods. Propane oxidation activity evaluations confirm that the photo-deposited and Mo-modified Pt/0.1Mo/SiO2-P catalyst exhibits the highest activity among all the prepared catalysts. Combined with experiments of C3H8-TPSR and in-situ DRIFT spectra of propane oxidation, it is found that the Pt/0.1Mo/SiO2-P catalyst remarkably promotes propane activation and C-H bond cleavage due to the nature change of Pt active sites, and the presence of gaseous oxygen benefits propane cleavage on active sites. Our primary results provide a promising strategy for designing superior platinum catalysts by regulating Pt active sites nature for efficient propane complete oxidation.

Microscopic investigation and local standard deviation analysis of liquid propane jets in supercritical environment

To improve the thermal efficiency of engines, the temperature and pressure in the combustion chamber are continually increased, potentially reaching the critical points of the fuels. Additionally, light fuels such as liquid ammonia and propane are utilized to reduce carbon emissions. The relatively low critical temperature of light fuels facilitates their transition into a supercritical state, which greatly change the jet characteristics. To gain a deeper understanding of the supercritical transition of fuels, jets of liquid propane are investigated through high-speed microscopic imaging technology, covering subcritical to supercritical environmental conditions. Liquid propane is injected through a transparent flat nozzle to observe the internal flow states within the nozzle. For image and data processing, local standard deviation (LSD) analysis and a Residual Network (ResNet-50) model are employed to identify the structures within the mixing region. Droplets counting and frequency domain analysis are also performed to reveal the features of supercritical transition. The findings highlight the importance of mask size in the jet feature extraction. Large mask highlights large scale structures including jet surface and mixing region structures, while small mask brings about full-scale feature including droplets and all other features. A criterion for mixing regime classification based on reduced temperature (Tr) and reduced pressure (Pr) is established directly from image data using the ResNet-50 model, where a condition of Tr1.6Pr0.4 ≥ 1.067 indicates a transcritical mixing regime. Both droplet counting and frequency domain analysis corroborate this mixing regime criterion. These insights enhance our understanding of supercritical transitions and are useful for simulation verifications.

Highly efficient La/Ni co-doped strontium titanate catalyst for co-production of propylene and hydrogen from propane in protonic ceramic electrochemical cells

A highly efficient La/Ni co-doped strontium titanate (LSNT) perovskite catalyst is developed and integrated in a protonic ceramic electrochemical cell for co-production of propylene and high-purity hydrogen from commercial propane feedstock. Propane conversion and hydrogen production rate can be effectively enhanced under an applied current due to the electrochemical promotion effect and/or shifted reaction equilibrium induced by rapid separation of hydrogen product. Water vapor in the feed gas could significantly improve the catalyst stability by suppressing the coke formation. The propane conversion could reach up to 53% at 600 °C under a current density of 90 mA cm−2. The LSNT catalyst also shows excellent tolerance for the sulfur contaminant in commercial propane gas. The excellent performance of the LSNT catalyst is attributed to the highly active and selective Ni species at the interface with the perovskite substrate, which are formed in situ via reduction-induced exsolution under reaction conditions.

Mechanism and Enantioselectivity in QUINOX-Catalyzed Asymmetric Allylations of Aromatic Aldehydes: Solvent and Substituent Effects.

Computational investigations were conducted on the QUINOX-catalyzed asymmetric allylation of aromatic aldehydes with allyltrichlorosilanes. Our calculations provide evidence that the catalytic allylation can follow distinct mechanisms, depending on the solvent employed. In toluene and CH2Cl2, the QUINOX-catalyzed allylation predominantly follows an associative pathway, while in CH3CN, a dissociative pathway becomes more favorable. Noncovalent interactions, such as π-stacking effects for the associative mechanism and CH/π interactions for the dissociative mechanism, play a pivotal role in enantiostereodifferentiation in the asymmetric QUINOX-catalyzed reactions of benzaldehyde. Furthermore, the study unveils how different aldehyde substituents exert differing influences on the catalytic allylation reaction. Specifically, the QUINOX-catalyzed allylation of 4-(trifloromethyl)benzaldehyde displays a strong preference for the associative pathway, yielding excellent results in both yield and enantioselectivity. Conversely, 4-methoxybenzaldehyde tends to favor a dissociative mechanism with reduced yields and enantioselectivity. The mechanistic basis for these remarkable substituent effects on the catalytic allylation reaction was also elucidated. In summary, this research enhances our understanding of the QUINOX-catalyzed asymmetric allylation, shedding light on the role of solvents and substituents in the reaction mechanism and enantioselectivity.

Phytochemical Studies of Alstonia scholaris, Chemical Transformation and Biological Evaluation against a Breast Cancer Cell Line

Background:: Some Alstonia species are used in traditional medicine to treat diseases such as cancer, dysentery, diarrhea, jaundice, malaria, gastrointestinal troubles, and snake-bites. Objective:: In this study, we aim to evaluate the ethanol leaf extract of Alstonia scholaris for anticancer constituents and structural modification to introduce a privilege medicinal α,β-unsaturated scaffold. Methods:: The relative viability of the MDA-MB-231 breast cancer cell line exposed to isolated compounds at different concentrations was assayed. Chemical analysis was carried out by high resolution mass spectrometry and one and two-dimensional NMR techniques. Results:: Structures of purified compounds were determined as betulin 1, α-amyrin acetate 2, mixture of β-sitosterol 3 and stigmasterol 4, tetratriacontyl-trans-p-coumarate 5, ursolic acid 6, β-sitosterol glucoside 7, picralstonine 8 and scholaricine 9. To introduce privilege medicinal scaffold, compounds 1 and 2 under SeO2 oxidation condition afford new acrylaldehye derivatines. Compound 1 afforded Betulin acrylaldehyde 10 while compound 2 afforded lupeolacetate acryl aldehyde 11 in an intriguing mechanism with the conversion of ursane to lupane scafford. Compound 11 equally showed interesting activity against MDA MB 231 breast cancer cell line with an IC50 of 4.63 ± 0.09 μg/ml. Conclusion:: From these findings, the medicinal α,β-unsaturated scaffold could have pharmacological effects in treating MDA-MB-231 breast cancer.

Synthesis and Sensing Response of Magnesium Antimoniate Oxide (MgSb2O6) in the Presence of Propane Atmospheres at Different Operating Voltages.

Nanoparticles of MgSb2O6 were synthesized using a microwave-assisted wet chemistry method, followed by calcination at 700 °C. Their ability to detect different concentrations of propane gas (C3H8) at various operating voltages was evaluated. The material's crystalline phase was identified using X-ray powder diffraction (XRD). The morphology was analyzed by scanning electron microscopy (SEM), finding bar- and polyhedron-type geometries. Through transmission electron microscopy (TEM), we found particle sizes of 8.87-99.85 nm with an average of ~27.63 nm. Employing ultraviolet-visible (UV-Vis) spectroscopy, we found a band gap value of ~3.86 eV. Thick films made with MgSb2O6 powders were exposed to atmospheres containing 150, 300, 400, and 600 ppm of propane gas for dynamic testing. The time-dependent sensitivities were ~61.09, ~88.80, ~97.65, and ~112.81%. In addition, tests were carried out at different operating voltages (5-50 V), finding very short response and recovery times (~57.25 and ~18.45 s, respectively) at 50 V. The excellent dynamic response of the MgSb2O6 is attributed mainly to the synthesis method because it was possible to obtain nanometric-sized particles. Our results show that the trirutile-type oxide MgSb2O6 possesses the ability, efficiency, and thermal stability to be applied as a gas sensor for propane.

Characterization of solid carbon from hydrocarbon pyrolysis in molten aluminum

This study analyzed the synthesized solid carbon from the pyrolysis of methane, ethane, propane, and natural gas using molten aluminum at 1000 °C. Microscopic examination revealed the formation of spherical structures and capped-carbon nanotubes with average primary particle sizes of 0.18–1.29 μm for the spheres and 0.31–0.39 μm for the capped-carbon nanotubes. Methane and ethane pyrolysis generated spherical carbon exclusively, while propane and natural gas pyrolysis produced spheres and capped-carbon nanotubes. The analysis of interlayer spacing indicated the presence of nanocrystalline properties in all carbon samples. X-ray diffraction analysis indicated broad graphitic phases in methane, ethane, and natural gas-derived carbon, and a broad and sharp graphitic carbon peak in propane-derived carbon. Raman spectroscopy confirmed the presence of graphitic structures and disorder, with capped-carbon nanotubes demonstrating more ordered structures than spheres. The thermogravimetric analysis uncovered differences in oxidation behavior, with the mixture of spherical carbon and capped-carbon nanotubes resulting from propane pyrolysis displaying superior thermal stability compared to samples composed solely of spherical carbon. Additionally, the solid carbon samples from the pyrolysis of methane, ethane, and natural gas displayed a final decomposition curve corresponding with commercial carbon black N991. The surface area analysis unveiled that carbon samples derived from ethane and natural gas exhibited surface areas that were 2.4–5.2 times larger than those of commercial carbon black N991 and graphite flakes. These findings underscore the adaptability of tailoring solid carbon materials by selecting the appropriate feed gas to suit specific applications.

Influence of updated isoprene oxidation mechanisms on the formation of intermediate and secondary products in MCM v3.3.1

In this study, we developed an observation based photochemical box model with the measurement data collected at a suburban site (i.e., the Xianghe, XH site) of the Beijing-Tianjin-Hebei (BTH) region and the latest version of the Master Chemical Mechanism (MCM v3.3.1), which newly incorporated 498 reaction for the additional 155 species with the oxidation of isoprene by the OH radical. The influence of updated isoprene degradation on the radical budgets, formation of intermediate and secondary products by comparing the simulation results in the original version (MCM v3.2) was firstly analyzed to estimate whether the updates of precursors could influence the model performance on its evolution pathways and related products. The results demonstrated that though the input of isoprene could significantly decrease or increase the concentrations of OH and HO2 radicals in the model simulation, respectively, the difference in the simulated concentrations of these radicals with isoprene oxidation before and after the updates was not statistically significant. For intermediate products, the simulated concentrations of formaldehyde and methacrolein (MACR) did not significantly alter before and after the updates, while the abundance of methyl vinyl ketone (MVK) reduced obviously (the maximum reduction of 31%) due to lower reaction coefficient between ISOPBO2 and NO and the lower branching ratios caused by the newly added pathways involving CISOPA and TISOPA in the updated scheme. On the other hand, the simulation concentrations of acrolein (ACR), glyoxal (Gly) and methylglyoxal (Mgly) increased significantly after the model updates. The dominant pathway for the increment of ACR was the decomposition of CH2CHCH2O produced by PE4E2CO, while those of Gly and Mgly were associated with radicals of C537O and PACLOOA that were both from the new intermediate radical of CISOPC. In addition, 39 isoprene oxidation products among the 155 new added species were identified to partition in the formation of secondary organic aerosol (SOA), which were coupled in the gas-particle partitioning module to optimize the formation of SOA, contributing 1.15 μg m−3 to the increase of SOA mean concentration. The updates of isoprene degradation further resulted in the significant change for its sensitivity in SOA formation, making it as the secondary important SOA precursor at the XH site. Last but not the least, the influence on photochemical ozone formation related to updates of isoprene degradation was ignorable. Overall, the above results confirmed the insufficient description of the degradation of precursors indeed limited the simulation of the intermediate and secondary products, highlighting the needs of exploring and parameterizing the precursor degradation processes for better understanding of their behaviors and SOA formation in the atmosphere.

Cardiac Radiofrequency Ablation Exacerbates Myocardial Injury through Pro-Inflammatory Response and Pro-Oxidative Stress in Elderly Patients with Persistent Atrial Fibrillation.

There is a need to assess myocardial damage after radiofrequency ablation of the pulmonary veins (PV) for persistent atrial fibrillation (PAF) in elderly patients. To evaluate oxidative stress, inflammatory response and myocardial damage in elderly patients with PAF after radiofrequency ablation of the PV. High-sensitivity troponin T (hsTnT), malondialdehyde-modified low-density lipoprotein (MDA-LDL), acrolein (ACR), lipid hydroperoxide (LHP), toll-like receptor 4 (TLR4), soluble growth stimulation expressed gene 2 (sST2), angiotensin II (Ang II) and myocardial blood flow (MBF) were determined before ablation and at 1, 3 and 5 months after radiofrequency ablation. The levels of hsTnT, MDA-LDL, ACR, LHP, TLR4, sST2 and Ang II were increased 3 months after ablations compared with before ablation and 1 month after ablation, respectively (P<0.001); they were further increased at 5 months after ablation compared with the 1- and 3-month groups, respectively (P<0.001). MBF was decreased in the 3 months group after ablations compared with before ablation and 1-month after ablation, respectively (P<0.001), and was further decreased in 5-months after ablations compared with 1-month and 3-month groups, respectively (P<0.001). Patients with epicardial monopolar radiofrequency ablation had higher levels of hsTnT, MDA-LDL, ACR, LHP, TLR4, sST2, Ang II and lower MBF than patients with endocardial monopolar and bipolar radiofrequency ablations, respectively (P<0.001). Monopolar radiofrequency ablation method could result in more myocardial injury than bipolar radiofrequency ablation. Oxidative stress and inflammatory response may be involved in cardiac radiofrequency ablation-induced myocardial injury, resulting in myocardial ischemia in elderly patients with PAF.

Design and simulation of 30 000 tons per year of cumene plant from natural gas field

Abstract The research considers the design and simulation of 30 000 tons per year of cumene plant using Aspen HYSYS as the simulation tool. The feed (material content) used is the characterized natural gas from Utorogu Gas Field with composition of 0.9019 methane, 0.0694 ethane, 0.0209 propane, 0.00361 n-butane, 0.00414 i-butane, 0.00005 n-pentane and 0.00007 i-pentane. The cumene plant consist of the cryogenic distillation column, de-hydrogenator (Continuous Stirred Tank Reactor), Alkylator (Plug Flow Reactor), storage tanks, separators, pumps, heat exchanger and mixers. The size/design models of basic plant units such as de-hydrogenator, alkylator, separators, storage tanks and distillation column were developed using the principles of mass and energy balance. The result of design or size specifications in terms of equipment diameter of basic plant units obtained from HYSYS simulation are 0.8 m and 0.319 m for the cryogenic and cumene columns; 1.931 m, 2.244 m and 1.366 m for the propane, propene and cumene storage tanks; 1.868 m and 2.076 m for the de-hydrogenator and alkylator; 1.931 m and 2.146 m for propene and cumene separators respectively. The power or capacity of propane and propene pumps configured in the plant are 0.02 kW and 0.005 kW respectively. The result of the reactor and distillation column thickness specification to withstand corrosion, pressure or stress during plant operation in terms of cylindrical shell and ellipsoidal doomed head are 17.36 mm and 4.31 mm respectively. The economic evaluation (overall cost) including the cost of utilities, catalyst, operating, and maintenance for entire plant is $ 3.004 M.