C1 C4 Research Articles

Description and evaluation of a detailed gas-phase chemistry scheme in the TM5-MP global chemistry transport model (r112)

Abstract. This work documents and evaluates the tropospheric gas-phase chemical mechanism MOGUNTIA in the three-dimensional chemistry transport model TM5-MP. Compared to the modified CB05 (mCB05) chemical mechanism previously used in the model, MOGUNTIA includes a detailed representation of the light hydrocarbons (C1–C4) and isoprene, along with a simplified chemistry representation of terpenes and aromatics. Another feature implemented in TM5-MP for this work is the use of the Rosenbrock solver in the chemistry code, which can replace the classical Euler backward integration method of the model. Global budgets of ozone (O3), carbon monoxide (CO), hydroxyl radicals (OH), nitrogen oxides (NOx), and volatile organic compounds (VOCs) are analyzed, and their mixing ratios are compared with a series of surface, aircraft, and satellite observations for the year 2006. Both mechanisms appear to be able to satisfactorily represent observed mixing ratios of important trace gases, with the MOGUNTIA chemistry configuration yielding lower biases than mCB05 compared to measurements in most of the cases. However, the two chemical mechanisms fail to reproduce the observed mixing ratios of light VOCs, indicating insufficient primary emission source strengths, oxidation that is too fast, and/or a low bias in the secondary contribution to C2–C3 organics via VOC atmospheric oxidation. Relative computational memory and time requirements of the different model configurations are also compared and discussed. Overall, the MOGUNTIA scheme simulates a large suite of oxygenated VOCs that are observed in the atmosphere at significant levels. This significantly expands the possible applications of TM5-MP.

Topological Regulation of the Bioactive Conformation of a Disulfide-Rich Peptide, Heat-Stable Enterotoxin.

Heat-stable enterotoxin (STa) produced by enterotoxigenic E. coli causes acute diarrhea and also can be used as a specific probe for colorectal cancer cells. STa contains three intra-molecular disulfide bonds (C1–C4, C2–C5, and C3–C6 connectivity). The chemical synthesis of STa provided not only the native type of STa but also a topological isomer that had the native disulfide pairings. Interestingly, the activity of the topological isomer was approximately 1/10–1/2 that of the native STa. To further investigate the bioactive conformation of this molecule and the regulation of disulfide-coupled folding during its chemical syntheses, we examined the folding mechanism of STa that occurs during its chemical synthesis. The folding intermediate of STa with two disulfide bonds (C1–C4 and C3–C6) and two Cys(Acm) residues, the precursor peptide, was treated with iodine to produce a third disulfide bond under several conditions. The topological isomer was predominantly produced under all conditions tested, along with trace amounts of the native type of STa. In addition, NMR measurements indicated that the topological isomer has a left-handed spiral structure similar to that of the precursor peptide, while the native type of STa had a right-handed spiral structure. These results indicate that the order of the regioselective formation of disulfide bonds is important for the regulation of the final conformation of disulfide-rich peptides in chemical synthesis.

RARE GENETIC DISORDER: HEREDITARY ANGIOEDEMA TYPE 1

SESSION TITLE: Medical Student/Resident Allergy and Airway Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Hereditary Angioedema is a rare genetic disorder characterized by recurrent episodes of angioedema without pruritus or urticaria, affecting the skin or mucosal tissues of the upper respiratory and GI tract. This is caused by a mutation in the SERPING1 gene, resulting in deficiency (type I) or dysfunction (type II) of C1 inhibitor protein. CASE PRESENTATION: A 43-year-old female with PMH of recurrent episodes of angioedema requiring intubation was admitted due to chief complaint of facial angioedema, hand and feet swelling associated with dyspnea, and stridor. Due to acute respiratory failure, emergent cricothyrotomy was attempted multiple times, and eventually open tracheostomy was performed and she was placed on mechanical ventilation. Simultaneously, the patient received dexamethasone, epinephrine, and famotidine. Work up revealed low levels of C1 inhibitor and C4, consistent with bradykinin-mediated hereditary angioedema type I. Rapid weaning from mechanical ventilation to a venturi mask was achieved. Her tracheostomy tube was changed to a Montgomery long-term cannula. Later, the Montgomery tube was changed to a #6 cuffless due to hemoptysis and posterior tracheal wall irritation. Her hospital course was complicated with supraglottic edema and grade 1 subglottic stenosis treated with subglottic balloon dilation and steroid Kenalog injection. Broad-spectrum antibiotics were administered due to purulent drainage around the tracheostomy site and thick sputum concerning for tracheobronchitis. The patient had significant improvement and was successfully capped. Due to exorbitant cost and limited insurance long term prophylaxis with Takhzyro (Lanadelumab), and Icatibant was not possible. She was started on Danazol 200 mg daily with 2 rescue doses of Takhzyro SC, 6 rescue doses of icatibant 30 mg SC, and EpiPen for respiratory distress. She was counseled to avoid any NSAIDs, ACEI, tamoxifen, and was discharged to another facility for rehabilitation and decannulation. DISCUSSION: This is a case describing a rare genetic disease, with a mortality rate of 30% due to asphyxiation from laryngeal edema that accounts for less than 1% of all the angioedema episodes. Laryngeal swelling usually develops around several hours (mean of 7h). There are 3 phases: predyspnea, dyspnea, and loss of consciousness phase ending with death; with an average length of 3.7h, 41 minutes, and 9 minutes respectively. CONCLUSIONS: Early diagnosis and education are paramount in these patients, to receive long term prophylaxis as C1 inhibitor concentrate, monoclonal antibody to kallikrein (lanadelumab), attenuated androgens; avoiding exacerbating factor; and being prepared for acute attacks with the same agents. Reference #1: .https://www.haea.org/assets/img/2013Recommendations.pdf Reference #2: Uptodate hereditary angioedema DISCLOSURES: No relevant relationships by Karim Anis, source=Web Response No relevant relationships by Lady Sanchez Fernandez, source=Web Response

Pd(II) and Rh(III) Complexes with Isoquinoline Derivatives Induced Mitochondria-Mediated Apoptotic and Autophagic Cell Death in HepG2 Cells

Nonplatinum metal complexes of [Pd(L1)Cl2] (C1), [Rh(L1)Cl3(DMSO)] (C2), [Pd(L2)Cl2] (C3), and [Rh(L3)Cl3(DMSO)] (C4) with isoquinoline derivatives have been prepared and characterized. C1–C4 exhib...

Formation kinetics of hydrocarbon compounds in the vacuum gas oil oxycracking process

The kinetics of the formation of oxygen-free hydrocarbon compounds obtained during the process of oxidation of vacuum gas oil at 450–550 °C for 2700 s of conducting of the process was studied. It was established that the highest rate of hydrocarbon formation was noted for the C1–C4 fraction starting from the moment the process started and up to 900 s (1.76 × 10−8 – 4.58 × 10−8). For other fractions, reaction rate maximums were noted: for C5–C9—300 s from the start of the process; for C10–C12—in the interval between 300 and 900 s, i.e. at 600 s process duration; for the raw fractions C22–C30, C31–C35 and C36–C40, grew after 1800s. The data on the influence of the process temperature on the rate of hydrocarbon formation allowed us to establish that the oxycracking process is limited by the formation of C10–C16 hydrocarbon fractions. The increase in contact time to a greater extent affects the rate of formation of hydrocarbons C1–C4 and C17–C21. The features of the rate of hydrocarbon production as a function of the amount of oxygen were found out: the rate of formation of hydrocarbons C1–C4 and C17–C21 increases with increasing oxygen content (in the case of C17–C21 it passes through a minimum); C5–C9 and C13–C16—monotonously decreases; C10–C12 passes through a maximum at an oxidation state of 1%, which undoubtedly indicates the role of oxygen in the destructive processes of the formation of hydrocarbons that do not contain oxygen under oxycracking conditions.

A comparative kinetic study of C8–C10 linear alkylbenzenes pyrolysis in a single-pulse shock tube

This work presents a comparative study on the pyrolysis of C8–C10 linear alkylbenzenes including ethylbenzene, n-propylbenzene and n-butylbenzene. Experiments were performed with highly diluted mixtures in argon containing respectively the three fuels under nearly identical conditions in a single-pulse shock tube, at a nominal pressure of 20 bar and over a temperature range of 950–1700 K. Post-shock gas mixtures were sampled and analyzed with the gas chromatographic technique so that species concentration evolutions as function of temperature were obtained for the pyrolysis of each fuel. A kinetic model was developed to interpret the similarities and differences regarding the fuel decomposition and species formation behaviors observed in the experiments. The fuel conversion of n-propylbenzene and n-butylbenzene proceeds along a similar curve, which is much faster than that of ethylbenzene. All three fuels are consumed mainly through the bond fission producing benzyl radical. The simultaneously formed C1–C3 alkyl radicals in separate cases significantly impact the fuel reactivity and the formation of small C1–C4 and monocyclic aromatic hydrocarbons. Specifically, in n-propylbenzene pyrolysis, the decomposition of ethyl radicals produces a considerable amount of hydrogen atoms, which enhances the reactivity of the reaction system and meanwhile results in relatively high production of benzene during the fuel consumption. The formation of other monocyclic aromatic hydrocarbon intermediates, such as toluene and styrene, is also influenced by fuel-related pathways. Concerning PAH formation, the kinetic schemes in the pyrolysis of linear C8–C10 alkylbenzenes are very similar, which are dominated by the reactions of benzyl and other resonantly-stabilized radicals produced from benzyl decomposition. The major PAH formation reactions are barely influenced by the fuel chemistry. The only notable fuel-specific pathway is the indene formation from 1-phenyl-2-propenyl in n-propylbenzene and n-butylbenzene pyrolysis at relatively low temperatures. Styrene is an abundant product and its reaction with phenyl is found to be an important channel of phenanthrene formation.

Phase Equilibria of Ternary Liquid–Liquid Systems (Water + C1–C4 Monocarboxylic Acids + Dibutyl Ether) at Three Different Temperatures: Modeling with A-UNIFAC

Liquid–liquid equilibrium (LLE) data for the ternary systems composed of water, C1–C4 monocarboxylic acids, and dibutyl ether were determined at three different temperatures (293.15, 303.15, and 313.15 K) and atmospheric pressure. The experimental solubility curves and mutual solubilities of (water + dibutyl ether) were determined by the cloud-point method, whereas the tie-lines of conjugate phases were obtained via GC analysis. The examined C1–C4 monocarboxylic acids are valuable components for estimating the effect of acid structure on LLE. The separation factor calculated from experimental LLE data is indicative of the ability of the solvent to effectively recover the acid. Equilibrium distribution of C1–C4 acids is better for more structured propionic and butyric acids as compared to less structured formic and acetic acids, and the general ranking with respect to the separation factor (S) follows the order: C4 > C3 > C2 > C1, and T293.15 < T303.15 ≤ T313.15. The LLE data were predicted with the group-contribution method A-UNIFAC with the newly estimated parameters, which shows an appropriate consistency with the experimental data.

Time to tracheostomy impacts overall outcomes in patients with cervical spinal cord injury.

The morbidity associated with cervical spine injury increases in the setting of concomitant cervical spinal cord injury (CSCI). A significant proportion of these patients require placement of a tracheostomy. However, it remains unclear if timing to tracheostomy following traumatic CSCI can impact outcomes. The aim of our study was to characterize outcomes associated with tracheostomy timing following traumatic CSCI. We performed a 5-year (2010-2014) analysis of the American College of Surgeons Trauma Quality Improvement Program database and included all adult (age, ≥18 years) trauma patients who had traumatic CSCI and received tracheostomy. Patients were subdivided into two groups: early tracheostomy (ET) (≤4 days from initial intubation) and late tracheostomy (LT) (>4 days). Outcome measures included respiratory complications, ventilator-free days, intensive care unit-free days and hospital length of stay, and mortality. Multivariate logistic regression analysis was performed. A total of 5,980 patients were included in the study, of which 1,010 (17%) patients received ET, while 4,970 (83%) patients received LT. Mean age was 46 years, and 73% were men. In terms of CSCI location, 48% of the patients had high CSCI (C1-C4), while 52% had low CSCI (C5-C7). Patients in the ET group had lower rates of respiratory complications (30% vs. 46%, p = 0.01), higher ventilator-free days (13 days vs. 9 days; p = 0.02), intensive care unit-free days (11 days vs. 8 days; p = 0.01), and a shorter hospital length of stay (22 days vs. 29 days; p = 0.01) compared with those in the LT group. On regression analysis, ET was associated with lower rates of respiratory complications in patients with high CSCI (odds ratio, 0.55 [0.41-0.81]) and low CSCI (odds ratio, 0.93 [0.72-0.95]). However, no association was found between time to tracheostomy and in-hospital mortality. Early tracheostomy regardless of CSCI level may lead to improved outcomes. Quality improvement efforts should focus on defining the optimal time to tracheostomy and considering ET as a component of SCI management bundle. Therapeutic, level IV.

Evaluation of biomolecular interactions and cytotoxic activity of organometallic binuclear Ru(II) complexes of ferrocenyl thiosemicarbazones

Four new ferrocenyl substituted thiosemicarbazone ligands (L1–L4) and their corresponding binuclear ruthenium(II) arene complexes of the general type [(η6-p cym)(L)Ru(μ-im)Ru(L)(η6-p-cym)]Cl (C1–C4) and [(η6-p cym)(L)Ru(μ-azpy)Ru(L)(η6-p-cym)]Cl2 (C5–C8) (cym = cymene, im = imidazole, azpy = 4,4′-azopyridine) have been synthesized and characterized. The structures of the complexes were established through DFT calculations and geometry optimization. The interactions of the binuclear complexes with DNA were investigated by absorption, emission and viscosity studies which indicated that the complexes bind to DNA via intercalation. Meanwhile, the interaction of complexes with the protein, bovine serum albumin (BSA), has also been studied using fluorescence emission spectroscopy. The experimental results show that the binuclear complexes exhibit good binding propensities to BSA. The complexes can quench the intrinsic fluorescence of BSA remarkably through a static or dynamic quenching process. In addition, the in vitro cytotoxicity of complexes C1–C8 against HeLa cell line was assayed which showed lower IC50 values indicating their higher cytotoxicity and potency in killing the cancer cells at low concentrations. Communicated by Ramaswamy H. Sarma

Development of a detailed pyrolysis mechanism for C1–C4 hydrocarbons under a wide range of temperature and pressure

AbstractA model of core mechanism of hydrocarbon pyrolysis with good predictive ability is crucial to the development of active cooling technology for advanced aeroengines. In this work, a detailed core kinetic model of pyrolysis of C1–C4 hydrocarbon fuels is developed through the combination of a series of potential energy surfaces and validated against a series of experimental results. The kinetic model contains 103 species and 1290 reactions, and most of the kinetic and thermochemical parameters are compiled from recent highly accurate quantum chemical calculations without modification. The pressure‐dependent rate constants are considered for the dissociation/association reactions, isomerization reactions, and chemically activated reactions. Simulation results for various alkanes (methane, ethane, propane, n‐butane, isobutane), alkenes (ethylene, propene, 1‐butene, 2‐butene, isobutene, allene, 1,3‐butadiene), and alkynes (acetylene, propyne, vinylacetylene) indicate that the major product distributions at various temperatures (800‐2300 K) and pressures (0.8‐10 atm) can be predicted well by the developed core kinetic model. Thus, the developed pyrolysis mechanism for C1–C4 hydrocarbons can be used as a cornerstone to develop the pyrolysis mechanisms of larger hydrocarbon fuels and thus support the development of thermal management in advanced aeroengines.

Identification and Validation of the Immune Subtypes of Lung Adenocarcinoma: Implications for Immunotherapy.

Lung adenocarcinoma (LUAD) is a devastating disease with poor patient survival. Cancer immunotherapy has revolutionized the treatment of LUAD, but only a limited number of patients effectively respond to this treatment. Thus, the work to elucidate the LUAD immune heterogeneity could be crucial in developing new immunotherapeutic strategies with better efficacy. Non-negative matrix factorization-based deconvolution was performed to identify robust clusters of 489 LUAD patients in The Cancer Genome Atlas (TCGA) and verify their reproducibility and stability in an independent LUAD cohort of 439 patients from the Gene Expression Omnibus (GEO). We used the graph learning-based dimensionality reduction to visualize the distribution of individual patients. In this study, four reproducible immune subtypes, Clusters 1–4 (C1–C4) associated with distinct gene module signatures, clinicopathological features, molecular and cellular characteristics were identified and validated. The immune-cold subtype, C3, was associated with the Dead event, the most advanced T stage, N stage, TNM stage and the worst prognosis for LUAD patients. Moreover, C3 exhibited the lowest infiltrating levels of B cells, T cell receptor (TCR) repertoire diversity and the highest level of neoantigen and mutation rate among C1–C4. On the other hand, the immune-hot subtype (C4) exhibited the highest infiltration of six types of infiltrating immune cells as well as the greatest leukocyte fraction, TCR and B cell receptor (BCR) repertoire diversity. C1 and C2 subtypes showed diverse clinicopathological and immunological features. Finally, our investigations discovered a complex immune landscape with a scattered immune subtype profile. This work may help inform immunotherapeutic decision-making and design advanced immunotherapy strategies for the treatment of lung cancer.

Conversion Kinetics of the Gaseous Products of Pyrolysis of Polypropylene and Waste Tires

Numerical simulations are performed of reaction kinetics in the gaseous products of pyrolysis of polypropylene and waste tires at atmospheric pressure in the temperature range of 800 to 1300 K. The initial conditions are set by using the experimental data available in the literature. The reactions between gaseous pyrolysis products are found to result in a decrease in the mixture’s temperature of polypropylene and a temperature increase for waste tires. The increase in the initial temperature reduces the gaseous product’s conversion for both polypropylene and the waste tires. It is established that the conversion pathways for the C1–C4 alkenes and alkanes strongly depend on the initial temperature and their initial composition.

Characterizing humic substances from a large-scale lake with irrigation return flows using 3DEEM-PARAFAC with CART and 2D-COS

The study was intended to determine whether the composition or distribution of humic substances from lake sediment could be characterized by spectroscopic data with chemometrics methods. The research materials were humic substances extracted from sediment samples collected in heavily polluted areas in Wuliangsuhai Lake. Humic substance extraction was performed using the method proposed by the International Humic Substances Society (IHSS). In extracted humic substances, the three-dimensional excitation–emission matrix (3DEEM) was determined, and parallel factor analysis (PARAFAC) with classification and regression trees (CART) and two-dimensional correlation spectra (2D-COS) was used to analyze spectroscopic data. Both the fulvic acid (FA) and the humic acid (HA) samples had five PARAFAC components (C1–C5), which contained Vis fulvic-like component (C1), Vis humic-like component (C2), UV humic-like component (C3), microbial fluorescent component (C4), and UV fulvic-like component (C5). This indicated the ubiquity of the humic substance components in the environment. For the CART analysis, C1 was the key factor used to differentiate FA and HA, while C1–C4 were the key parameters used to distinguish the humic substance samples in the eight units. Using 2D-COS and hetero 2D-COS, the PARAFAC components were formed with the increasing of sediment depth in the following order: C3 → C2 → C5 → C4 → C1, which suggested that the relatively labile structure appeared earlier than the relatively stable structure with the greater depth of the sediment. The Vis fulvic-like could be a key factor used to discriminate the FA and the HA fractions, while the latent factors of different depths of sediment were not identical. The order of the humic substance formations was Vis humic-like → UV humic-like → Vis fulvic-like → microbial fluorophore → UV fulvic-like.

Comparative Life-Cycle Assessment of a High-Rise Mass Timber Building with an Equivalent Reinforced Concrete Alternative Using the Athena Impact Estimator for Buildings

Buildings consume large amounts of materials and energy, making them one of the highest environmental impactors. Quantifying the impact of building materials can be critical to developing an effective greenhouse gas mitigation strategy. Using Athena Impact Estimator for Buildings (IE4B), this paper compares cradle-to-grave life-cycle assessment (LCA) results for a 12-story building constructed from cross-laminated timber (CLT) and a functionally equivalent reinforced concrete (RC) building. Following EN 15978 framework, environmental impacts for stages A1–A5 (product to construction), B2, B4, and B6 (use), C1–C4 (end of life), and D (beyond the building life) were evaluated in detail along resource efficiency. For material resource efficiency, total mass of the CLT building was 33.2% less than the alternative RC building. For modules A to C and not considering operational energy use (B6), LCA results show a 20.6% reduction in embodied carbon achieved for the CLT building, compared to the RC building. For modules A to D and not considering B6, the embodied carbon assessment revealed that for the CLT building, 6.57 × 105 kg CO2 eq was emitted, whereas for the equivalent RC building, 2.16 × 106 kg CO2 eq was emitted, and emissions from CLT building was 70% lower than that from RC building. Additionally, 1.84 × 106 kg of CO2 eq was stored in the wood material used in the CLT building during its lifetime. Building material selection should be considered for the urgent need to reduce global climate change impacts.

From Extra Virgin Olive Oil to Refined Products: Intensity and Balance Shifts of the Volatile Compounds versus Odor.

To explore relationships between the volatile organic compounds (VOCs) of different grades of olive oils (OOs) (extra virgin olive oil (EVOO), refined olive oil (ROO), and pomace olive oil (POO)) and odor quality, VOCs were measured in the headspace of the oils by proton transfer reaction quadrupole ion guide time-of-flight mass spectrometry. The concentrations of most VOCs differed significantly between the grades (EVOO > ROO > POO), whereas the abundance of m/z 47.012 (formic acid), m/z 49.016 (fragments), m/z 49.027 (fragments), and m/z 115.111 (heptanal/heptanone) increased in that order. Although the refined oils had considerably lower VOC abundance, the extent of the decline varied with the VOCs. This results in differences in VOCs proportions. The high VOC abundance in the EVOO headspace in comparison to ROO and POO results in a richer and more complex odor. The identified C5–C6 compounds are expected to contribute mainly to the green odor notes, while the identified C1–C4 and C7–C15 are mainly responsible for odor defects of OOs. Current results reveal that processing strongly affects both the quantitative and relative abundance of the VOCs and, therefore, the odor quality of the various grades of OOs.

Production routes of advanced renewable C1 to C4 alcohols as biofuel components – a review

AbstractIn 2018, the EU's revised Renewable Energy Directive came into force, increasing renewable energy targets for all energy sectors while limiting the use of first‐generation biomass as feedstock. Fuel components like methanol, ethanol, propanols, and butanols represent promising candidates to enable the targets for transportation to be achieved because they can be used with existing infrastructure and can be further processed to give additives and substitutes. A wide variety of feedstocks and processes are available for this purpose. In this review, the thermocatalytic and biological synthesis routes for C1–C4 alcohol fuels are summarized to illustrate the many alternatives. They include biomass and waste gasification and carbon capture and utilization to obtain syngas for catalytic conversion, fermentation of sugars from lignocellulosic feedstock, and novel, less developed pathways like syngas fermentation, glycerol conversion, and biogas reforming. The current state of technology is presented by discussing the advantages and technical hurdles, and by introducing recent scaled‐up approaches. This demonstrates the need for further research and development. The assessment of techno‐economic analyses in the literature illustrates the dominant factors affecting production costs and reveals the broad range of feasibility of the various production routes. The review shows that the routes most similar to conventional, well‐established syntheses bear the highest potential to be implemented in the short and medium term. The availability of cheap and abundant feedstock also plays a crucial role. Methanol synthesis from biomass gasification and ethanol, and acetone‐butanol‐ethanol fermentation from lignocellulosic biomass, are therefore considered to be very promising. © 2020 The Authors. Biofuels, Bioproducts and Biorefining published by Society of Industrial Chemistry and John Wiley &amp; Sons Ltd.

Synthesis, characterization and antimicrobial activity of palladium(II) complexes with O,O'-dialkyl esters of (S,S)-ethylenediamine-N,N'-di-(3,3′-1H-indol-3yl)-propionic acid

A series of four new ligands of general formula R2-S,S-eddtrp·2HCl (L1–L4) and their palladium(II) complexes of general formula [PdCl2(R2-S,S-eddtrp)] (C1–C4) where R = ethyl, 1-propyl, 1-butyl and 1-pentyl; S,S-eddtrp·2HCl = ethylenediamine-N,N′-di-(3,3′-1H-indol-3yl)propionic acid dihydrochloride have been synthesized and characterized by elemental microanalysis, infrared, 1H and 13C NMR spectroscopy. The proposed structures of all compounds were examined by density functional theory (DFT). The ligands (L1–L4) and Pd(II) complexes (C1–C4) were screened for their antimicrobial activity against 19 microorganisms and minimum inhibitory concentrations (MIC) and minimum microbicidal concentration (MMC) were determinated. All tested ligands and complexes exhibited the highest antimicrobial activity on Escherichia coli ATCC 25922, being in range or higher than positive control, tetracycline.

Characterization of an indoor environmental chamber and identification of C1–C4 OVOCs during isoprene ozonolysis

An environmental chamber was built up and characterized at The Hong Kong Polytechnic University. The chamber consists of a 6 m3 poly tetrafluoroethylene-co-perfluoropropyl vinyl ether Teflon film reactor inside a stainless-steel enclosure stocked with a series of online gas-phase and aerosol-phase analytical instruments. Temperature and relative humidity are controllable and can be set to a range of 10–40 ± 1°C and 5–85%, ± 3%, respectively. An air purification system provides zero air for the chamber with concentrations of total volatile organic compounds &lt; 1 ppb, NOX and O3 &lt; 1 ppb and particles concentration &lt; 102 particles·cm−3. Characterization experiments were performed under dry conditions (relative humidity&lt; 5%) and ambient temperature (25°C). Average wall loss rates of O3 and NO2 were observed as 2.92 × 10−6 s−1 and 9.3 × 10−4 s−1 respectively, and the particle wall loss rate was 0.27 h−1. Dark ozonolysis of isoprene was studied using this chamber and the production of C1–C4 oxygenated volatile organic compounds such as formaldehyde, methacrolein and methyl vinyl ketone (MVK) was identified using proton-transfer-reaction time-of-flight mass spectrometry. Results of experiments indicate that this new facility can be used to investigate and simulate the gaseous chemistry and secondary aerosol formation.

Electron impact ionization and fragmentation of biofuels

We present in this article, a review of our recent experimental and theoretical studies published in the literature on electron impact ionization and fragmentation of the primary alcohols methanol, ethanol, 1-propanol and 1-butanol (C1–C4). We discuss the mass spectra (MS) of these alcohols, measured for the electron impact energy of 70 eV and also, total (TICS) and partial (PICS) ionization cross sections in the energy range from 10 to 100 eV, which revealed the probability of forming different cations, by either direct or dissociative ionization. These experimental TICS are summarized together with theoretical values, calculated using the Binary-encounter Bethe (BEB) and the independent atom model with the screening corrected additivity rule (IAM-SCAR) methods. Additionally, we compared data of appearance energies – AE and discussed the application of the extended Wannier theory to PICS in order to produce the ionization and ionic fragmentation thresholds for the electron impact of these alcohols.

Palladium‐Based Catalysts Supported by Unsymmetrical XYC–1 Type Pincer Ligands: C5 Arylation of Imidazoles and Synthesis of Octinoxate Utilizing the Mizoroki–Heck Reaction

A series of new unsymmetrical (XYC–1 type) palladacycles (C1–C4) were designed and synthesized with simple anchoring ligands L1–4H (L1H = 2‐((2‐(4‐methoxybenzylidene)‐1‐phenylhydrazinyl)methyl)pyridine, L2H = N,N‐dimethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono)methyl)aniline, L3H = N,N‐diethyl‐4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono)methyl) aniline and L4H = 4‐(4‐((2‐phenyl‐2‐(pyridin‐2‐ylmethyl)hydrazono) methyl)phenyl)morpholine H = dissociable proton). Molecular structure of catalysts (C1–C4) were further established by single X‐ray crystallographic studies. The catalytic performance of palladacycles (C1–C4) was explored with the direct Csp2–H arylation of imidazoles with aryl halide derivatives. These palladacycles were also applied for investigating of Mizoroki–Heck reactions with aryl halides and acrylate derivatives. During catalytic cycle in situ generated Pd(0) nanoparticles were characterized by XPS, SEM and TEM analysis and possible reaction pathways were proposed. The catalyst was employed as a pre‐catalyst for the gram‐scale synthesis of octinoxate, which is utilized as a UV‐B sunscreen agent.