Two-dimensional coordination polymer with tellurium nodes

Bis(diphenylphosphino)hexane disulfide and TeCl₄ afforded layered network coordination polymer with Te(II) nodes. The two-dimensional nets are positively charged, the anions and form layers alternating the polymeric networks.     

The Organization of the Quorum Sensing luxI/R Family Genes in Burkholderia

Members of the Burkholderia genus of Proteobacteria are capable of living freely in the environment and can also colonize human, animal and plant hosts. Certain members are considered to be clinically important from both medical and veterinary perspectives and furthermore may be important modulators of the rhizosphere. Quorum sensing via N-acyl homoserine lactone signals (AHL QS) is present in almost all Burkholderia species and is thought to play important roles in lifestyle changes such as colonization and niche invasion. Here we present a census of AHL QS genes retrieved from public databases and indicate that the local arrangement (topology) of QS genes, their location within chromosomes and their gene neighborhoods show characteristic patterns that differ between the known Burkholderia clades. In sequence phylogenies, AHL QS genes seem to cluster according to the local gene topology rather than according to the species, which suggests that the basic topology types were present prior to the appearance of current Burkholderia species. The data are available at http://net.icgeb.org/burkholderia/.     

iNR-Drug: Predicting the Interaction of Drugs with Nuclear Receptors in Cellular Networking

Nuclear receptors (NRs) are closely associated with various major diseases such as cancer, diabetes, inflammatory disease, and osteoporosis. Therefore, NRs have become a frequent target for drug development. During the process of developing drugs against these diseases by targeting NRs, we are often facing a problem: Given a NR and chemical compound, can we identify whether they are really in interaction with each other in a cell? To address this problem, a predictor called “iNR-Drug” was developed. In the predictor, the drug compound concerned was formulated by a 256-D (dimensional) vector derived from its molecular fingerprint, and the NR by a 500-D vector formed by incorporating its sequential evolution information and physicochemical features into the general form of pseudo amino acid composition, and the prediction engine was operated by the SVM (support vector machine) algorithm. Compared with the existing prediction methods in this area, iNR-Drug not only can yield a higher success rate, but is also featured by a user-friendly web-server established at http://www.jci-bioinfo.cn/iNR-Drug/, which is particularly useful for most experimental scientists to obtain their desired data in a timely manner. It is anticipated that the iNR-Drug server may become a useful high throughput tool for both basic research and drug development, and that the current approach may be easily extended to study the interactions of drug with other targets as well.     

Optimizing Chain Topology of Bottle Brush Copolymer for Promoting the Disorder-to-Order Transition

The order-disorder transitions (ODT) of core-shell bottle brush copolymer and its structural isomers were investigated by dissipative particle dynamics simulations and theoretically by random phase approximation. Introducing a chain topology parameter λ which parametrizes linking points between M diblock chains each with N monomers, the degree of incompatibility at ODT ((χN)ODT; χ being the Flory–Huggins interaction parameter between constituent monomers) was predicted as a function of chain topology parameter (λ) and the number of linked diblock chains per bottle brush copolymer (M). It was found that there exists an optimal chain topology about λ at which (χN)ODT gets a minimum while the domain spacing remains nearly unchanged. The prediction provides a theoretical guideline for designing an optimal copolymer architecture capable of forming sub-10 nm periodic structures even with non-high χ components.     

Liquid–liquid equilibrium for the system n-heptane+o-xylene+triethylene glycol from 293.1 to 323.1 K

Extraction of xylenes from straight-run naphtha streams, using a suitable solvent, is an important industrial application. This study is concerned with the experimental investigation of the LLE of n-heptane+o-xylene+triethylene glycol (TEG) at 293.1, 303.1, 313.1 and 323.1 K. Results from three versions of model, as provided in (a sequential simulator), are compared to the experimental data. These versions, which differ only in the database for the mutual group interaction parameters, are the standard (with group interaction parameters extracted from vapor–liquid-equilibrium (VLE) databank), - (with group interaction parameters extracted from liquid–liquid-equilibrium databank), and - (with group interaction parameters extracted from the Dortmund Data bank). The comparison is made in terms of root-mean-square (RMS) and the average-absolute deviations (AAD) in compositions. The performance of and - in describing the experimental data has been found comparable and better than that of -     

SSGraphCPI: A Novel Model for Predicting Compound-Protein Interactions Based on Deep Learning

Identifying compound-protein (drug-target, DTI) interactions (CPI) accurately is a key step in drug discovery. Including virtual screening and drug reuse, it can significantly reduce the time it takes to identify drug candidates and provide patients with timely and effective treatment. Recently, more and more researchers have developed CPI’s deep learning model, including feature representation of a 2D molecular graph of a compound using a graph convolutional neural network, but this method loses much important information about the compound. In this paper, we propose a novel three-channel deep learning framework, named SSGraphCPI, for CPI prediction, which is composed of recurrent neural networks with an attentional mechanism and graph convolutional neural network. In our model, the characteristics of compounds are extracted from 1D SMILES string and 2D molecular graph. Using both the 1D SMILES string sequence and the 2D molecular graph can provide both sequential and structural features for CPI predictions. Additionally, we select the 1D CNN module to learn the hidden data patterns in the sequence to mine deeper information. Our model is much more suitable for collecting more effective information of compounds. Experimental results show that our method achieves significant performances with RMSE (Root Mean Square Error) = 2.24 and R2 (degree of linear fitting of the model) = 0.039 on the GPCR (G Protein-Coupled Receptors) dataset, and with RMSE = 2.64 and R2 = 0.018 on the GPCR dataset RMSE, which preforms better than some classical deep learning models, including RNN/GCNN-CNN, GCNNet and GATNet.     

Transcranial Magnetic Stimulation of the Supplementary Motor Area in the Treatment of Obsessive-Compulsive Disorder: A Multi-Site Study

Recently, strategies beyond pharmacological and psychological treatments have been developed for the management of obsessive-compulsive disorder (OCD). Specifically, repetitive transcranial magnetic stimulation (rTMS) has been employed as an adjunctive treatment in cases of treatment-refractory OCD. Here, we investigate six weeks of low frequency rTMS, applied bilaterally and simultaneously over the sensory motor area, in OCD patients in a randomized, double-blind placebo-controlled clinical trial. Twenty-two participants were randomly enrolled into the treatment (ACTIVE = 10) or placebo (SHAM = 12) groups. At each of seven visits (baseline; day 1 and weeks 2, 4, and 6 of treatment; and two and six weeks after treatment) the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) was administered. At the end of the six weeks of rTMS, patients in the ACTIVE group showed a clinically significant decrease in Y-BOCS scores compared to both the baseline and the SHAM group. This effect was maintained six weeks following the end of rTMS treatment. Therefore, in this sample, rTMS appeared to significantly improve the OCD symptoms of the treated patients beyond the treatment window. More studies need to be conducted to determine the generalizability of these findings and to define the duration of rTMS’ clinical effect on the Y-BOCS. Clinical Trial Registration Number (NCT) at www.clinicaltrials.gov: {"type":"clinical-trial","attrs":{"text":"NCT00616486","term_id":"NCT00616486"}}NCT00616486.     

Optimization of the Freeze-Drying Cycle: A New Model for Pressure Rise Analysis

Abstract

The principal aim of this study was to evaluate the Pressure Rise Analysis (PRA) method as a nonintrusive method for monitoring the product temperature during primary drying of the freeze-drying process of model pharmaceutical formulations. The principle of this method, based on the MTM method initially published by Milton et al.1 Milton, N., Pikal, M.J., Roy, M.L. and Nail, S.L. 1997. Evaluation of manometric temperature measurement as a method of monitoring product temperature during lyophilization. PDA Journal of Pharmaceutical Science and Technology, 51(1): 7–16. [PUBMED][INFOTRIEVE][CSA][PubMed] , [Google Scholar] consisted in interrupting rapidly the water vapor flow from the sublimation chamber to the condenser chamber and by analyzing the resulting dynamics of the chamber total pressure increase. A new physical model, named PRA model, based on elementary heat and mass balance equations and on constitutive equations expressing the elementary fluxes, was proposed and validated in this study for interpreting the experimental pressure rise data. It was possible to identify very precisely the values of some key parameters of the freeze-drying process such as the ice sublimation interface temperature, the mass transfer resistance of the dried layer and the overall heat transfer coefficient of the vial. The identified ice front temperatures were compared with experimental data obtained from vial bottom temperatures measured by thin thermocouples during freeze-drying runs of 5% w/v mannitol solutions. These two sets of data were found consistent with a maximum difference of no more than 2°C. The dried layer mass transfer resistance increased linearly as a function of its thickness, and the values were coherent with the few literature data published for this system. The method also led to reliable values of the vial overall heat transfer coefficient of approximately 20 Wm^?2 K^?1 in accordance with the published data for this type of vials and these experimental freeze-drying conditions.     

SYNTHESES OF ADDUCTS OF ACTIVE METABOLITES OF CARCINOGENIC POLYCYCLIC AROMATIC HYDROCARBONS WITH 2′-DEOXYRIBONUCLEOSIDES

Syntheses are reported for: (1 Harvey, R. G. 1991. Polycyclic Aromatic Hydrocarbons: Chemistry and Carcinogenicity, Cambridge, , U.K.: Cambridge University Press.  [Google Scholar]) adducts of the quinone metabolites of benzo[a]pyrene (BPQ) and benz[a]anthracene (BAQ) with 2′-deoxyadenosine and 2′-deoxyguanosine; (2 Conney, A. H. 1982. Induction of Microsomal Enzymes by Foreign Chemicals and Carcinogenesis by Polycyclic Aromatic Hydrocarbons. Cancer Res., 42: 4875–4917. [PUBMED][INFOTRIEVE][CSA][PubMed], [Web of Science ®] , [Google Scholar]) ¹⁵ N-labelled analogs of these adducts (four or five nitrogen atoms ¹⁵ N-labelled); (3 Dipple, A. 1994. “Reactions of Polycyclic Aromatic Hydrocarbons with DNA”. In DNA Adducts: Identification and Biological Significance, Edited by: Hemminki, K., Dipple, A., Segerbäck, D., Kadulbar, F. F., Shuker, D. and Bartsch, H. pp. 107–129. IARC Scientific Publication No. 125.  [Google Scholar]) depurinated adducts of BPQ and BAQ with adenine or guanine covalently linked to the N7 or N9 positions of the purine bases; (4 Jeffrey, A. M., Weinstein, I. B., Jennette, K., Grzeskowiak, K., Nakanishi, K., Harvey, R. G., Autrup, H. and Harris, C. 1977. Structures of Benzo[a]pyrene-Nucleic Acid Adducts Formed in Human and Bovine Bronchial Explants. Nature (London)., 269: 348–350. [CSA][CROSSREF][Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) ¹³ C-labelled derivatives of benzo[a]pyrene, BPQ, benzo[a]pyrene trans-7,8-dihydrodiol, and the benzo[a]pyrene anti-diol epoxide (with ¹³ C-atoms at the 5- and 11-positions); and (5 Jennette, K., Jeffrey, A. M., Blobstein, S. H., Beland, F. A., Harvey, R. G. and Weinstein, I. B. 1977. Characterization of Nucleoside Adducts from the in Vitro Reaction of Benzo[a]pyrene-7,8-dihydrodiol-9,10-oxide or Benzo[a]pyrene-4,5-oxide with Nucleic Acids. Biochemistry, 16: 932–938. [PUBMED][INFOTRIEVE][CSA][CROSSREF][Crossref], [PubMed], [Web of Science ®] , [Google Scholar]) depurinated adducts formed by reactions of the benzo[a]pyrene radical-cation at the C ⁸ -, N ⁷ -, and N ⁹ -positions of adenine and guanine.     

A Numerical Study of Calm Air Sampling with a Blunt Sampler

The performance of an idealized spherical sampler facing both vertically upwards and downwards in calm air is studied numerically. To describe the air flow around the sampler, both potential and viscous flow models have been adopted. The equations of particle motion are then solved to calculate the aspiration efficiency. The dependence of the aspiration efficiency upon the various parameters of importance in calm air sampling are investigated and compared where possible with the experimental work of Su and Vincent (2003 Su, W. C. and Vincent, J. H. 2003. Experimental Measurements of Aspiration Efficiency for Idealized Spherical Aerosol Samplers in Calm Air. J. Aerosol Sci., 34: 1151–1165. [CSA][CROSSREF][Crossref], [Web of Science ®] , [Google Scholar], 2004a Su, W. C. and Vincent, J. H. 2004a. Experimental Measurements and Numerical Calculations of Aspiration Efficiency for Cylindrical Thin-Walled Aerosol Samplers in Perfectly Calm Air. Aerosol Sci. Tech., 38: 766–781. [CSA][CROSSREF][Taylor & Francis Online], [Web of Science ®] , [Google Scholar], b Su, W. C. and Vincent, J. H. 2004b. Towards a General Semi-Empirical Model for the Aspiration Efficiencies of Aerosol Samplers in Perfectly Calm Air. J. Aerosol Sci., 35: 1119–1134. [CSA][CROSSREF][Crossref] , [Google Scholar]).

It is found that in the case of upwards sampling the bluntness of the sampler only has a significant effect upon aspiration for large sampling velocities, values that would not generally be physically realistic. In the case of downwards sampling an important non-dimensional quantity, B ² R _C , is identified, where B represents the sampler bluntness and R _C represents the gravitational effects. This quantity determines the physical conditions for which aspiration will not occur and also the limiting values of the aspiration efficiency when aspiration does occur. In the case of low sampling velocities a difference is noted between experimental and numerical results for aspiration efficiency raising the need for more experimental data in this area. For both upwards and downwards sampling the semi-empirical models of Su and Vincent (2004b) Su, W. C. and Vincent, J. H. 2004b. Towards a General Semi-Empirical Model for the Aspiration Efficiencies of Aerosol Samplers in Perfectly Calm Air. J. Aerosol Sci., 35: 1119–1134. [CSA][CROSSREF][Crossref] , [Google Scholar] have been modified to account for the information gained from the study. This is particularly important in the downwards sampling case where the modified model is found to agree particularly well with the results obtained.     

iRSpot-TNCPseAAC: Identify Recombination Spots with Trinucleotide Composition and Pseudo Amino Acid Components

Meiosis and recombination are the two opposite aspects that coexist in a DNA system. As a driving force for evolution by generating natural genetic variations, meiotic recombination plays a very important role in the formation of eggs and sperm. Interestingly, the recombination does not occur randomly across a genome, but with higher probability in some genomic regions called “hotspots”, while with lower probability in so-called “coldspots”. With the ever-increasing amount of genome sequence data in the postgenomic era, computational methods for effectively identifying the hotspots and coldspots have become urgent as they can timely provide us with useful insights into the mechanism of meiotic recombination and the process of genome evolution as well. To meet the need, we developed a new predictor called “iRSpot-TNCPseAAC”, in which a DNA sample was formulated by combining its trinucleotide composition (TNC) and the pseudo amino acid components (PseAAC) of the protein translated from the DNA sample according to its genetic codes. The former was used to incorporate its local or short-rage sequence order information; while the latter, its global and long-range one. Compared with the best existing predictor in this area, iRSpot-TNCPseAAC achieved higher rates in accuracy, Mathew’s correlation coefficient, and sensitivity, indicating that the new predictor may become a useful tool for identifying the recombination hotspots and coldspots, or, at least, become a complementary tool to the existing methods. It has not escaped our notice that the aforementioned novel approach to incorporate the DNA sequence order information into a discrete model may also be used for many other genome analysis problems. The web-server for iRSpot-TNCPseAAC is available at http://www.jci-bioinfo.cn/iRSpot-TNCPseAAC. Furthermore, for the convenience of the vast majority of experimental scientists, a step-by-step guide is provided on how to use the current web server to obtain their desired result without the need to follow the complicated mathematical equations.     

Selective Deflection and Localization of Flowing Aerosols onto a Substrate

Pulsed airflow cued by the fluorescence spectrum of a particular aerosol can be used to distinguish and deflect particles of biological origin out of an aerosol stream, permitting concentration of these particles for subsequent analysis (Pan et al. 2004 Pan, Y. L., Boutou, V., Bottiger, J. R., Zhang, S. S., Wolf, J. P. and Chang, R. K. 2004. A Puff of Air Sorts Bioaerosols for Pathogen Identification. Aerosol Sci. Technol., 38: 598–602. [CROSSREF][CSA][Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). However, these high velocity pulses of air have an inherent tendency to scatter particles, confounding efforts to concentrate these deflected particles for analysis. The ability to concentrate large numbers of biological particles into a small area on a collection substrate is particularly important for more species-specific techniques such as Raman and FTIR (Fourier Transform Infra-Red) spectroscopy, which require long integration times due to their weak signal strength. In the present work, a simple method is developed for deflecting and localizing particles after classification by a pulsed airflow. The concept is both modeled and experimentally tested. A specially designed funnel is used to localize the scattered particles onto an area of substrate as small as 1 mm in diameter. Computational fluid dynamics simulations were performed to investigate the interaction of the pulsed airflow with the deflected particles and the localizing funnel, in order to gain insight into design parameters and operating conditions that affect the efficiency of this technique. The results show that the combination of pulsed airflow with a localizing funnel effectively deflects and localizes the concentrated bioaerosol onto a small area of substrate or an opening of a microfluidic cell.     

Comparative Evaluation of the Effects of Ozone,Diode Laser,and Traditional Cavity Disinfectants on Microleakage

Aim: This study aimed to evaluate the effects on microleakage of the application of ozone gas, laser and traditional cavity disinfection under in vitro conditions.

Material and Methods: Ninety third-molar teeth extracted for various reasons were used in this study. All the teeth were prepared with a standard V cavity on the buccal surface. Then the teeth were randomly allocated to one of 6 groups of 15 teeth; Group 1 benzalkonium chloride, Group 2 chlorhexidine gluconate, Group 3 sodium hypochloride, Group 4 diode laser, Group 5 ozone gas, Group 6 control group- no disinfection was applied. Primer was applied to the cavities, then bond and 10-s polymerization. Clearfil AP-X was used in the cavities as a hybrid composite and polymerized for 20 s. The samples then underwent 1000 thermal cycles of 30-s application, in baths at temperatures between 5 ± 2 °C and 55 ± 2 °C. All the samples were stirred in 0.5% basic phuxine solution and the sections taken under stereomicroscope were examined and photographed at 15 × magnification. SEM analysis was made and the obtained results were statistically evaluated with the Kruskal–Wallis test.

Results: No significant difference was seen between the groups in respect of the microleakage values of both the occlusal and gingival edges (p < 0.05). Comparison of the microleakage values of the occlusal and gingival edges of the groups determined the least leakage to be in the ozone group (p < 0.05).

Conclusion: No statistical significance was determined between the groups. However, the mean least microleakage was found in the ozone group and the highest amount in the control group.     

Synthesis and dynamic mechanical study of core–shell structure epoxy/polyacrylate composite particle

A material with high damping property and based on epoxy/polyacrylate (EP/PA) composite particles was synthesized by two-stage emulsion polymerization. Transmission electron microscopy (TEM) showed that the composite particles have a spherical morphology, a core–shell structure and a diameter of 100 nm–130 nm. Fourier transform infrared spectra (FTIR) indicated the cross-linking between EP groups in the core layer and carboxyl groups in the shell layer of the composite particles during film formation. The cross-linking reaction improved the dynamic mechanical property by the interaction of core and shell polymers. The effects of the cross-linking agent and ratio of the two polymers on the damping capacity were studied by dynamic mechanical analysis (DMA). DMA results revealed that a certain amount of acrylic acid could markedly enhance the loss factor (tan δ) and slightly widen the damping temperature range. When the EP/PA ratio was 1:7, peak values for tan δ of the composite materials could reach 2.10, exceeding the value for most damping materials. The result implies that the EP/PA composites have great potential application in damping steel surface coatings.     

Surface charge heterogeneity of kaolinite in aqueous suspension in comparison with montmorillonite

An analogous study to 2:1 type montmorillonite [Tombácz, E., Szekeres, M., 2004. Colloidal behavior of aqueous montmorillonite suspensions: the specific role of pH in the presence of indifferent electrolytes. Appl. Clay Sci. 27, 75–94.] was performed on 1:1 type kaolinite obtained from Zettlitz kaolin. Clay minerals are built up from silica tetrahedral (T) and alumina octahedral (O) layers. These lamellar particles have patch-wise surface heterogeneity, since different sites are localized on definite parts of particle surface. pH-dependent charges develop on the surface hydroxyls mainly at edges besides the permanent negative charges on silica basal plane due to isomorphic substitutions. Electric double layers (edl) with either constant charge density on T faces (silica basal planes) or constant potential at constant pH on edges and O faces (hydroxyl-terminated planes) form on patches. The local electrostatic field is determined by the crystal structure of clay particles, and influenced by the pH and dissolved electrolytes. The acid–base titration of Na-kaolinite suspensions showed analogous feature to montmorillonite. The initial pH of suspensions and the net proton surface excess vs. pH functions shifted to the lower pH with increasing ionic strength indicating the presence of permanent charges in both cases, but these shifts were smaller for kaolinite in accordance with its much lower layer charge density. The pH-dependent charge formation was similar, positive charges in the protonation reaction of (Si–O)Al–OH sites formed only at pHs below  6–6.5, considered as point of zero net proton charge (PZNPC) of kaolinite particles. So, oppositely charged surface parts on both clay particles are only below this pH, therefore patch-wise charge heterogeneity exists under acidic conditions. Electrophoretic mobility measurements, however, showed negative values for both clays over the whole range of pH showing the dominance of permanent charges, and only certain decrease in absolute values, much larger for kaolinite was observed with decreasing pH below pH  6. The charge heterogeneity was supported by the pH-dependent properties of dilute and dense clay suspensions with different NaCl concentrations. Huge aggregates were able to form only below pH  7 in kaolinite suspensions. Coagulation kinetics measurements at different pHs provided undisputable proofs for heterocoagulation of kaolinite particles. Similarly to montmorillonite, heterocoagulation at pH  4 occurs only above a threshold electrolyte concentration, which was much smaller, only  1 mmol l^− 1 NaCl for kaolinite, than that for montmorillonite due to the substantial difference in particle geometry. The electrolyte tolerance of both clay suspensions increased with increasing pH, pH  6–6.5 range was sensitive, and even a sudden change occurred above pH  6 in kaolinite. There was practically no difference in the critical coagulation concentration of kaolinite and montmorillonite (c.c.c. 100 mmol l^− 1 NaCl) measured in alkaline region, where homocoagulation of negatively charged lamellae takes place. Rheological measurements showed shear thinning flow character and small thixotropy of suspensions at and above pH  6.7 proving the existence of repulsive interaction between uniformly charged particles in 0.01 M NaCl for both clays. The appearance of antithixotropy, the sudden increase in yield values, and also the formation of viscoelastic systems only at and below pH  6 verify the network formation due to attraction between oppositely charged parts of kaolinite particles. Under similar conditions the montmorillonite gels were thixotropic with significant elastic response.     

The physical state of Ga species in Ga-containing mordenite zeolites

A thorough characterization of mordenite zeolites containing framework Ga and Al atoms over the entire compositional range 0  Ga/(Ga + Al)  1 prepared under wholly inorganic conditions has been done by using powder X-ray diffraction, elemental analysis, N₂ adsorption, scanning and transmission electron microscopies, multinuclear MAS NMR, X-ray photoelectron spectroscopy, and X-ray absorption fine structure. Unlike the case of their as-made Na⁺ form, calcination of the -exchanged form of Ga-substituted mordenite materials at elevated temperatures leads to a severe extraction of framework Ga atoms from the tetrahedral positions. Most of the extraframework Ga species were found to remain tetrahedrally coordinated within mordenite micropores in a highly dispersed manner and to become octahedrally coordinated under dehydrating conditions.     

Topological analysis of catalytic reaction networks: Methanol decomposition on Pt(111)

We describe our new reaction route (RR) graph approach as a powerful new tool for topological mechanistic and kinetic analysis of catalytic reaction networks, illustrated here with the help of methanol decomposition on Pt(111). In this approach a graph-theoretic network of molecular reaction steps is first constructed for the overall reaction (OR), on which each mechanistic step is represented by a directed branch interconnected at nodes, such that all conceivable reaction pathways can then be traced on it simply as walks or paths. Further, the network is consistent with the basic laws of flow graphs, so that it is suitable for a quantitative analysis. In fact, a direct analogy can be made to an equivalent wiring diagram, which allows tools of electric circuit analysis, namely, Kirchhoff's laws of current (rate) and potential (affinity), to be directly utilized for a rigorous flux analysis of the network. As a result, the dominant pathways as well as the rate-limiting steps (RLS) become transparent. This furthermore facilitates network pruning to retain only the essential steps and pathways. The RR graph approach when combined with ab initio kinetics, thus, provides a rigorous new framework for analyzing the mechanism and kinetics of catalytic reactions. It is, thus, found that methanol decomposition proceeds exclusively via the initial CH dehydrogenation step rather than through OH bond activation.     

Development of kinetic model for the reaction between SO2/NO and coal fly ash/CaO/CaSO4 sorbent

Sorbents for semidry-type flue gas desulfurization (FGD) process can be synthesized by mixing coal fly ash, calcium oxide, and calcium sulfate in a hydration process. As sorbent reactivity is directly correlated with the specific surface area of the sorbent, reacting temperature, concentration of the reacting gas species and relative humidity, two major aim in the development of a kinetic model for the FGD process are to obtain an accurate model and at the same time, incorporating all the parameters above. Thus, the objective of this work is to achieve these two aims. The kinetic model proposed is based on the material balance for the gaseous and solid phase using partial differential equations incorporating a modified surface coverage model which assumes that the reaction is controlled by chemical reaction on sorbent grain surface. The kinetic parameters of the mathematical model were obtained from a series of experimental desulfurization reactions carried out under isothermal conditions at various operating parameters; inlet concentration of SO₂ (500 ppm  C_0,SO2  2000 ppm), inlet concentration of NO (250 ppm  C_O,NO  750 ppm), reaction temperature (60 °C  T  80 °C) and relative humidity (50%  RH  70%). For a variety of initial operating conditions, the mathematical model is shown to give comparable predictive capability when used for interpolation and extrapolation with error less than 7%. The model was found useful to predict the daily operation of flue gas desulfurization processes by using CaO/CaSO₄/coal fly ash sorbent to remove SO₂ from flue gas.