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Co-pyrolysis of plastics and biomass turns the environmental burden of waste plastics into opportunities for fuel production. This work comparatively studied the co-pyrolysis characteristics of Thlaspi arvenseL. seed (TS) and several plastics (polyethylene (PE), polypropylene (PS), polyvinyl chloride (PVC)) with different mass fractions. By comparing the co-pyrolysis results of TS-plastic mixtures with the weighted results of their individual pyrolysis, synergistic effects were evaluated. Thermogravimetric analysis demonstrated that co-pyrolysis delayed the appearance of peaks for the maximum thermal weight loss of PS-TS mixtures, and PVC-TS mixtures exhibited the opposite behavior. The addition of PE mainly caused the appearance of more aliphatic hydrocarbons in product distributions, and the content increased by 16.91% at most (in 1PE1TS), while the PS, and PVC with TS exhibited better monocyclic aromatic hydrocarbon selectivity when they were co-pyrolyzed, and the highest content was 47.26% in 7PVC3TS mixture. Co-pyrolysis effectively inhibited the production of oxygenated compounds, especially the production of fatty acids, and the highest reduction was 20.33% (in 3PS7TS). The activation energy (E) was calculated by the Flynn-Wall-Ozawa (FWO) method. The results showed that E was optimal when the mixing ratio of plastic and TS was 3:7. Furthermore, the reaction process mechanism was examined by using the Criado method. [ABSTRACT FROM AUTHOR]

Organosolv-phase oxidization pretreatment of corncob (OOPC) at ambient pressure and temperature coupled with fast pyrolysis was first performed. The effects of organosolv/water phase with/without oxidation, Fe2+ contents, H 2 O 2 concentrations, pyrolytic behavior, and kinetic analysis on the distributions of pyrolytic products were investigated. The yields of higher oxygen-containing components such as anhydrosugars were obtained from fast pyrolysis of OOPC in comparison with raw, organosolv-phase, and water-phase oxidization pretreated corncobs. With the increase Fe2+ contents and H 2 O 2 concentrations during organosolv-phase oxidization pretreatment, the O/C ratios (0.35–0.51), levoglucosan yield (2.2–160.2 mg/g), and relative content of anhydrosugars (5.5–72.9 %) were remarkably improved whereas the yield of pyrolytic chars (21.4–13.4 %) and average E values (65.5–50.4 kJ/mol) significantly decreased compared to raw sample. The pyrolysis products of OOPC were remarkably transformed from low-molecular compounds of raw sample to high-molecular compounds. The higher Fe2+ contents and H 2 O 2 concentrations were conductive to the elimination of biomass resistant and the formation of oxygen-rich fractions mainly consisting of considerable amounts of C–O, O–C O, and –OH bonds due to the effective removal of carbon-rich fractions (C–C bonds), which were responsible for the increase in anhydrosugars. [Display omitted] • Organosolv-phase oxidization pretreated corncobs (OOPCs) before pyrolysis was first performed. • The OOPCs reacted at normal temperature and pressure formed oxygen-rich fractions. • The pyrolysis products of OOPCs transformed higher oxygen-containing components. • Levoglucosan yield obtained from fast pyrolysis of OOPCs improved significantly. • The yield of pyrolytic char and average E value significantly decreased by OOPCs pyrolysis. [ABSTRACT FROM AUTHOR]

Telomerases are moderately processive reverse transcriptases that use an integral RNA template to extend the 3′ end of linear chromosomes. Processivity values, defined as the probability of extension rather than dissociation, range from about 0.7 to 0.99 at each step. Consequently, an average of tens to hundreds of nucleotides are incorporated before the single-stranded sDNA product dissociates. The RNA template includes a six nucleotide repeat, which must be reset in the active site via a series of translocation steps. Nucleotide addition associated with a translocation event shows a lower processivity (repeat addition processivity, RAP) than that at other positions (nucleotide addition processivity, NAP), giving rise to a characteristic strong band every 6th position when the product DNA is analyzed by gel electrophoresis. Here, we simulate basic reaction mechanisms and analyze the product concentrations using several standard procedures to show how the latter can give rise to systematic errors in the processivity estimate. Complete kinetic analysis of the time course of DNA product concentrations following a chase with excess unlabeled DNA primer (i.e., a pulse-chase experiment) provides the most rigorous approach. This analysis reveals that the higher product concentrations associated with RAP arise from a stalling of nucleotide incorporation reaction during translocation rather than an increased rate constant for the dissociation of DNA from the telomerase.

The slow reaction rates to chemical and photochemical degradation are well-known properties of plastics. However, large plastic surfaces exposed to environmental conditions release particles and compounds that affect ecosystems and human health. The aim of this work was to identify compounds associated with the degradation of polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) microplastics (markers) on silica and sand and evaluate their use to screen microplastics on natural sand. Products were identified by using targeted and untargeted LC-HRMS analysis. All polymers underwent chemical oxidation on silica. PE released dicarboxylic acids (HO 2 C-(CH 2 ) n -CO 2 H ( n = 4-30), while PS released cis / trans -chalcone, trans -dypnone, 3-phenylpropiophenone, and dibenzoylmethane. PVC released dicarboxylic acids and aromatic compounds. Upon irradiation, PE was stable while PS released the same compounds as under chemical oxidation but at lower yields. Under the above condition, PVC generated HO 2 C-[CH 2 -CHCl] n -CH 2 -CO 2 H and HO 2 C-[CH 2 -CHCl] n -CO 2 H ( n = 2-19) dicarboxylic acids. The same products were detected on sand but at a lower concentration than on silica due to better retention within the pores. Detection of markers of PE and PS on natural sand allowed us to screen microplastics by following a targeted analysis. Markers of PVC were not detected before or after thermal/photo-oxidation due to the low release of compounds and limitations associated with surface exposure/penetration of radiation.

Abstract We build upon recent advances on the distributional aspect of Stein's method to propose a novel and flexible technique for computing Stein operators for random variables that can be written as products of independent random variables. We show that our results are valid for a wide class of distributions including normal, beta, variance-gamma, generalized gamma and many more. Our operators are k th degree differential operators with polynomial coefficients; they are straightforward to obtain even when the target density bears no explicit handle. As an application, we derive a new formula for the density of the product of k independent symmetric variance-gamma distributed random variables. [ABSTRACT FROM AUTHOR]

In this paper, a carbonization process for valid liquid–solid separation and upgrading of coal liquefaction residues was proposed and practiced using batch-type devices. The effect of carbonization times and temperatures on the efficiency of liquid–solid separation and product distributions were investigated using self-prepared liquid–solid mixtures (CSMs) from direct coal liquefaction. It was suggested that the carbonization temperature and blowing gases were essential to the efficient liquid–solid separation in this process, and the carbonization process was characterized by the efficient liquid–solid separation. The n -hexane soluble fractions (HS) can be largely separated from CLMs. It was remarkable that over 0.06–1.50% of HSs can be additionally produced at the higher temperatures (430 °C–500 °C). On the other hand, the obtained semi-cokes (SCs) were mainly characterized as a rich carbon-containing material with high heating values. Some of the SCs were characterized by the better caking property with the caking index ( G ) from 68.5 to 75.2. In addition, it was proved that the caking property of SCs is directly affected by the asphaltenes (ASs) instead of pre-asphaltenes (PAs). [ABSTRACT FROM AUTHOR]

To investigate synergetic effects on pyrolysis of municipal solid waste and corn stalk, pyrolysis characteristics and product distributions of their mixtures were examined by thermal gravimetric and fixed-bed. Results indicated that co-pyrolysis process can be divided into four steps: losing water, main pyrolysis, carbonization and catalytic gasification of char. Under different blending ratio conditions, char and liquid yields were lower than the theoretical values calculated on pyrolysis of each individual sample, and consequently, gas yields were higher. Linear relationship can be applied to char and liquid products, however, hardly applied to gas yields. [ABSTRACT FROM AUTHOR]

The effect of hydrothermal treatment (HTT) on Chinese fan palm pyrolysis was investigated. It indicated that HTT could effectively remove a large portion of alkali/alkaline earth metals and disrupt the chemical structure to a certain extent. HTT delayed the initial decomposition temperature but accelerated the pyrolysis process completely. HTT also increased the relative contents of both sugars and hydrocarbons in pyrolysis. At 210 °C, HTT had the most significant promotion effect on the sugars formation with the relative content of 30.58%. While, The relative content of phenols, acids, furans, aldehydes, esters and CO 2 decreased more or less after HTT. With increasing pyrolysis temperature, the relative content of most groups of chemicals except hydrocarbons decreased. Response contours were analyzed to find the optimal reaction conditions for generating acids, phenols, sugars and hydrocarbons, respectively. The results indicated both pyrolysis temperature and HTT temperature had distinct influence on relative contents of products. [ABSTRACT FROM AUTHOR]

We derive the characteristic function (CF) for two product distributions—first for the product of two Gaussian random variables (RVs), where one has zero mean and unity variance, and the other has arbitrary mean and variance. Next, we develop the characteristic function for the product of a gamma RV and a zero mean, unity variance Gaussian RV. The underlying rationale for this is to develop a model for a “quasi-Gaussian” RV—an RV that is nominally Gaussian, but with mean and variance parameters that are not constant, but instead, are RVs themselves. Due to the central limit theorem, many “real-world” processes are modeled as being Gaussian distributed. However, this implicitly assumes that the processes being modeled are perfectly stationary, which is often a poor assumption. The quasi-Gaussian model could be used as a more conservative description of many of these processes. [ABSTRACT FROM AUTHOR]

A detailed theoretical investigation on the thermal decomposition and isomerization of 3-Me-1-heptyl radical is performed at the ab initio CBS-QB3 level of theory. The calculation reveals that the detailed reaction mechanisms of 3-Me-1-heptyl radical mainly incorporate reversible intramolecular hydrogen atom transfer and the beta-site C C bond scission. The standard reaction enthalpies ( Δ r H 298 0 ) and enthalpies of formation ( Δ f H 298 0 ) are determined at the CBS-QB3 level of theory. All investigated decomposition reactions are generally endothermic, while most of the isomerization processes are exothermic. Among the hydrogen atom transfer processes, the 1,3- and 1,2-hydrogen atom migration (R 5 and R 6 , respectively) are prohibited due to their high isomerization barriers, while the 1,6-(R 2 ) and 1,5-hydrogen atom transfer (R 3 ) are kinetically accessible (owing to their low ring strains in the cyclic transition states). Compared with the 1,5-hydrogen atom shift for the n -heptyl radical, the methyl-substitution increases the rate coefficient by a factor of about 3.0. The product distributions are predicted at different temperatures on the basis of the steady-state approximation (SSA). The ultimate and dominant products majorly include ethylene (C 2 H 4 ), propylene (C 3 H 6 ), 1-butylene (1-C 4 H 8 ) and 2-hexene (2-C 6 H 12 ) over the temperature range of 500–2500 K. [ABSTRACT FROM AUTHOR]

The product distributions and gaseous product composition during the co-pyrolysis of platanus wood (PW) and bituminous coal were explored by employing a drop tube fixed-bed reactor. The pore properties of co-pyrolytic char were investigated via Brunauer-Emmett-Teller (BET) and fractal theory analyses. Synergistic effects were examined by comparing the experimental and theoretical product yields, gas compositions, and fractal dimensions (D) of residual char. Complex synergistic effects affecting product yield and gas composition were observed. Significant positive synergistic effects promoting gas formation were found with 50% PW mass ratio within the temperature scope of 800–1000 °C. In contrast, negative synergistic effects inhibited the formation of char and liquid products. The H 2 composition increased owing to the positive synergistic effects at a pyrolysis temperature of 1000 °C, whereas remarkable positive synergistic effects on CO generation were observed with 30% PW blending ratio from 600° to 700°C. PW promoted the specific surface area of co-pyrolytic char. The D values of co-pyrolytic char increased as the PW blending proportion was enlarged. Moreover, the D of residual char indicated higher values than the theoretical results. The higher content of volatile matter and the existence of alkali and alkaline-earth metals in PW were beneficial for forming mesopores and micropores with pore aperture of smaller than 10 nm, resulting in the complexity promotion of the pore structure. An exponential correlation between D and surface area was observed. This study provides important information for devising and optimizing co-pyrolysis systems for biomass and coal. • Influence of platanus wood on product distributions and char pore structure was explored. • The PW promoted gas yield while reduced char and liquid yields compared with theoretical. • Positive or negative synergistic effects occurred on the compositions of gaseous product. • Fractal dimension indicated PW promoted the pore development of co-pyrolytic char. [ABSTRACT FROM AUTHOR]

Quasiclassical trajectory calculations have been performed for the OH + CO reaction at zero total angular momentum and collision energies up to 0.4 eV. Calculations have been carried out on the same potential energy surface which was used for full-dimensional state-to-state quantum dynamical calculation. The resulting quasiclassical total reaction probability as well as the product rotational and vibrational distributions have been analyzed and compared with the outcomes of a pseudo-quantization treatment of the product vibrational energy. Energy-conserving classical trajectories reproduce fairly well all the quantum features but the oscillatory patterns, whereas this does not apply to the energy non-conserving ones. Total reaction probabilities obtained from quasiclassical calculations at several fixed total angular momentum are also compared with centrifugal sudden quantum results. These results have also allowed to investigate the effect of the total angular momentum on the translational energy and angular distributions of the products. [ABSTRACT FROM AUTHOR]

Abstract: An extensive quasiclassical investigation in a quantum spirit of the OH+CO→H+CO2 reaction on the three most popular potential energy surfaces has been performed. Using the standard, the Gaussian and the one dimensional Gaussian binning techniques, product angular and translational energy distributions were calculated and compared with those obtained from the molecular beam experiments. Such a comparison shows that pseudoquantization methods hardly improve the agreement. An analysis of the convergence of the binning methods on the number of reactive trajectories used to calculate the product distributions was also carried out proving that a huge number of trajectories are needed to obtain accurate results in the Gaussian binning case against a significantly lower number in the standard and one dimensional Gaussian binning procedures. Finally, product vibrational distributions of the CO2 molecule were also calculated via pseudoquantization of the vibrational energy of products. Unfortunately, experimental data are not available for comparison. [ABSTRACT FROM AUTHOR]

grid empowered molecular simulator (GEMS) embodying in a single workflow the ab initio treatment of elementary chemical processes has been extended to four atom reactions. GEMS has been used to carry out a massive quasiclassical investigation for the $$\hbox{OH} +\hbox{CO} \rightarrow\hbox{H} +\hbox{CO}_2$$ reaction on the most recently proposed potential energy surface. The type of potential energy surface used and the possibility of running the simulations on the grid have allowed us to keep the error of the order of a few percent at all values of the collision energy and to estimate accurately the dependence of the reaction cross section on the collision energy. The accuracy of the calculations has allowed to unequivocally single out the fact that the calculated center-of-mass angular distribution is clearly isotropic and radically differs from the asymmetric forward-backward structure obtained from the experiment. However, when the laboratory frame analogues are compared, the difference almost vanishes. [ABSTRACT FROM AUTHOR]

A Boolean function f is correlation immune if each input variable is independent of the output, under the uniform distribution on inputs. For example, the parity function is correlation immune. We consider the problem of identifying relevant variables of a correlation immune function, in the presence of irrelevant variables. We address this problem in two different contexts. First, we analyze Skewing, a heuristic method that was developed to improve the ability of greedy decision tree algorithms to identify relevant variables of correlation immune Boolean functions, given examples drawn from the uniform distribution (Page and Ray, 2003). We present theoretical results revealing both the capabilities and limitations of skewing. Second, we explore the problem of identifying relevant variables in the Product Distribution Choice (PDC) learning model, a model in which the learner can choose product distributions and obtain examples from them. We prove a lemma establishing a property of Boolean functions that may be of independent interest. Using this lemma, we give two new algorithms for finding relevant variables of correlation immune functions in the PDC model. [ABSTRACT FROM AUTHOR]

We consider the problem of learning mixtures of product distributions over discrete domains in the distribution learning framework introduced by Kearns et al. [Proceedings of the 26th Annual Symposium on Theory of Computing (STOC), Montréal, QC, 1994, ACM, New York, pp. 273-282]. We give a poly(n/ ϵ)-time algorithm for learning a mixture of κ arbitrary product distributions over the n-dimensional Boolean cube {0, 1}n to accuracy ϵ, for any constant κ. Previous polynomial-time algorithms could achieve this only for κ = 2 product distributions; our result answers an open question stated independently in [M. Cryan, Learning and Approximation Algorithms for Problems Motivated by Evolutionary Trees, Ph.D. thesis, University of Warwick, Warwick, UK, 1999] and [Y. Freund and Y. Mansour, Proceedings of the 12th Annual Conference on Computational Learning Theory, 1999, pp. 183-192]. We further give evidence that no polynomial-time algorithm can succeed when κ is superconstant, by reduction from a difficult open problem in PAC (probably approximately correct) learning. Finally, we generalize our poly(n/ ϵ)-time algorithm to learn any mixture of κ = O(1) product distributions over {0, 1, . . . , b - 1}n, for any b = O(1). [ABSTRACT FROM AUTHOR]

• NaOH and CaCl 2 improved the dewatering properties of oily scum. • Compared with NaOH, CaCl 2 had a stronger dewatering ability. • The chemical compounds in the liquid product from oily scum HT were obtained. • The combustion behaviors of the obtained hydrochars were evaluated. Hydrothermal treatment (HT) is used to upgrade oily scum for its disposal and utilization. The effects of sodium hydroxide (NaOH) and calcium chloride (CaCl 2) on the dewatering properties and product characteristics of oily scum via HT were investigated in this study. Results showed that NaOH and CaCl 2 proved effective in terms of increasing the liquid product and decreasing the moisture content in hydrochars. Compared with NaOH, CaCl 2 resulted in a higher liquid product and a greater moisture removal capacity after HT of oily scum. The addition and adding concentrations of NaOH or CaCl 2 had significant influences on combustion behaviors of hydrochars. The combustion kinetic parameters of hydrochars derived from HT of oily scum with NaOH or CaCl 2 were obtained. The results can provide valuable reference for enhancing the dewaterability and resource utilization of oily scum. [ABSTRACT FROM AUTHOR]

Telomerases are moderately processive reverse transcriptases that use an integral RNA template to extend the 3′ end of linear chromosomes. Processivity values, defined as the probability of extension rather than dissociation, range from about 0.7 to 0.99 at each step. Consequently, an average of tens to hundreds of nucleotides are incorporated before the single-stranded sDNA product dissociates. The RNA template includes a six nucleotide repeat, which must be reset in the active site via a series of translocation steps. Nucleotide addition associated with a translocation event shows a lower processivity (repeat addition processivity, RAP) than that at other positions (nucleotide addition processivity, NAP), giving rise to a characteristic strong band every 6th position when the product DNA is analyzed by gel electrophoresis. Here, we simulate basic reaction mechanisms and analyze the product concentrations using several standard procedures to show how the latter can give rise to systematic errors in the processivity estimate. Complete kinetic analysis of the time course of DNA product concentrations following a chase with excess unlabeled DNA primer (i.e., a pulse-chase experiment) provides the most rigorous approach. This analysis reveals that the higher product concentrations associated with RAP arise from a stalling of nucleotide incorporation reaction during translocation rather than an increased rate constant for the dissociation of DNA from the telomerase. [ABSTRACT FROM AUTHOR]

This paper presents a polynomial-time algorithm for inferring a probabilistic generalization of the class of read-once Boolean formulas over the usual basis { AND, OR, NOT }. The algorithm effectively infers a good approximation of the target formula when provided with random examples which are chosen according to any product distribution, i.e., any distribution in which the setting of each input bit is chosen independently of the settings of the other bits. Since the class of formulas considered includes ordinary read-once Boolean formulas, our result shows that such formulas are PAC learnable (in the sense of Valiant) against any product distribution (for instance, against the uniform distribution). Further, this class of probabilistic formulas includes read-once formulas whose behavior has been corrupted by large amounts of random noise. Such noise may affect the formula's output ('misclassification noise'), the input bits ( 'attribute noise'), or it may affect the behavior of individual gates of the formula. Thus, in this setting, we show that read-once formula's can be inferred (approximately), despite large amounts of noise affecting the formula's behavior. [ABSTRACT FROM AUTHOR]

• ReaxFF parameters were developed by training QM results with Monte Carlo Annealing method. • Molecular dynamics simulations were employed to determine the reaction mechanisms, rate constants and product distributions. • Thermal decomposition of Heptafluoroisobutyronitrile and its gas mixture under engineering condition were simulated with ReaxFF method. Heptafluoroisobutyronitrile (i -C 3 F 7 CN, C4) has obtained widely attention accounts for its good dielectric property and low GWP as a potential alternative gas. To investigate the thermal decomposition characteristics of C4, new reactive force field (ReaxFF) parameters were developed by training against QM-derived calculations with Monte Carlo Annealing (MC) method. The reliability of new parameters was verified not only by the deviations between QM-based calculations and ReaxFF predictions but also by good agreement between molecular dynamics (MD) simulations and experimental results. Hence, various NVT-MD simulations were employed to determine the reaction mechanisms, rate constants and product distributions. Our simulation results showed that the C4 decay was fitted with first-order kinetic expression, and the apparent activation energy was predicted to be 33.9 ± 1.67 kcal/mol. The main products of C4 decomposition were CF 4 , C 2 F 6 , C 3 F 6 , FCN, CF 3 CN, C 2 F 5 CN, which were in accordance with experimental and theoretical results. As for the initial reactions, we noted that C-CF 3 bond was revealed to be the weakest bond and followed by C-F and C-CN bonds in C4 as reported in previous work. Similar MD simulation was conducted with C4/CO 2 mixture system, which suggested that CO 2 could consume F and CF 3 radicals, resulting in significant impacts for CF 4 and FCN. Noteworthy, new products (CO, COF 2) were also seen as observed experimentally. To investigate the C4/CO 2 system under the moisture condition, C4/CO 2 with 1% H 2 O content was performed and new toxic gas HF was observed as a characteristic product, indicating an unnegligible impact by water content. [ABSTRACT FROM AUTHOR]

• Initial reaction mechanism was investigated by single molecule ReaxFF molecular dynamics simulation. • The main thermal decomposition products of vegetable insulating oils predicted by ReaxFF. • The product distributions of vegetable insulating oils thermal decomposition over the temperature range of 1000–5000 K were explored. Thermal decomposition reaction mechanisms and product distributions of vegetable oils were studied using reactive force field (ReaxFF) molecular dynamics (MD) simulations. The initial decomposition process, initiated by ester bond cleavages, followed by decarboxylation reactions and C C bond cleavages, was suggested by monitoring reaction trajectories and supported via QM calculations. The main decomposition products predicted by ReaxFF method were CH 4 , C 2 H 2 , C 2 H 4 , C 2 H 6 , C 3 H 6 , CO 2 , CO, H 2 , H 2 O, showing a good agreement with experimental results. In addition, the temperature impacts on product distributions were also carried out to determine characteristic products under different conditions. Accordingly, we noted that the most abundant product switched from (CO 2 and C 2 H 4) to H 2 along with the temperature increasing, which supplied new insights for the thermal decomposition of vegetable insulating oils. [ABSTRACT FROM AUTHOR]

The catalytic combustion characteristics of methane-air mixtures in small-scale systems were investigated at elevated temperatures, with particular emphasis on identifying the main factors that affect formation and removal of combustion-generated pollutants. Computational fluid dynamics simulations were performed using detailed chemical kinetic mechanisms, and more insights were offered into the phenomena occurring in the temperature range where homogeneous and heterogeneous reaction pathways are both important. Reaction engineering analysis was performed to provide an in-depth understanding of how to achieve low emissions of pollutants. Spatial distributions of the major species involved were presented to gain insight into the interplay between the two competing pathways involved. The results indicated that the distribution of oxidized products depends critically on the feed composition, dimension, temperature, and pressure. Small-scale catalytic systems enable low emissions of pollutants even in a high temperature environment, along with high combustion efficiency. The interplay between the two competing pathways via radicals is strong, and the heterogeneous pathway can significantly inhibit the homogeneous pathway. The inhibiting effect also accounts for the low emissions of nitrogen oxides. Almost all of the nitrogen oxides emitted by small-scale catalytic systems are nitric oxide. Catalytic combustion technology can be used to reduce the formation of undesired products, especially pollutant nitrogen oxide gases far below what can be achieved without catalysts. Recommendations for the design of small-scale catalytic systems are provided. [ABSTRACT FROM AUTHOR]