Role of rhenium in bimetallic reforming catalysts

The influence of rhenium on the behavior of a Pt/Al₂O₃ catalyst was studied in n-hexane reaction by means of dilution of the catalyst bed with Re/Al₂O₃. Parallel to activity, selectivity and ageing data obtained in slug pulse and continuous flow reactors, the amount of the surface carbon formed during the reaction was determined and its reactivity in hydrogen atmosphere was also studied. It is suggested that in the presence of rhenium due to the increase in the amount of hydrogen available for hydrogen consuming reactions including hydrodepolymerization of the carbonaceous surface overlayer, the routes of ageing processes are changed, resulting in lower carbon content on the catalyst and less pronounced catalyst deactivation.

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Pt/Al₂O₃ -, Re/Al₂O₃. , , , , . , , , , , , , .

     

Catalyst selectivity in thiophene hydrodesulfurization: Effect of H2S and aging

The distribution of hydrodesulfurization (HDS) products of thiophene was compared on 9 different catalysts at different degrees of sulfidation and at aging in H₂/thiophene mixtures. The main products of HDS were C₄ and C_l-C₃ hydrocarbons. The effect of sulfur uptake on the productsmin distribution was similar for Co and Ni promoted, and reverse to that on Pd and Pt promoted samples. The effect of aging was similar for all samples. This revised version was published online in August 2006 with corrections to the Cover Date.     

Reactivity of the carbonaceous surface overlayer on supported platinum catalysts studied by high temperature pyrolysis gas chromatography

The reactivity of the carbonaceous surface overlayer formed on Pt/Al₂O₃ catalysts in n-hexane dehydrocyclization has been studied by high temperature Pyrolysis Gas Chromatography. This method can be used to characterize surface carbon overlayers formed on different catalysts in the course of hydrocarbon reactions.

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, Pt/Al₂O₃ -, . , .

     

Cannabis-Derived Compounds Cannabichromene and Δ9-Tetrahydrocannabinol Interact and Exhibit Cytotoxic Activity against Urothelial Cell Carcinoma Correlated with Inhibition of Cell Migration and Cytoskeleton Organization

Cannabis sativa contains more than 500 constituents, yet the anticancer properties of the vast majority of cannabis compounds remains unknown. We aimed to identify cannabis compounds and their combinations presenting cytotoxicity against bladder urothelial carcinoma (UC), the most common urinary system cancer. An XTT assay was used to determine cytotoxic activity of C. sativa extracts on T24 and HBT-9 cell lines. Extract chemical content was identified by high-performance liquid chromatography (HPLC). Fluorescence-activated cell sorting (FACS) was used to determine apoptosis and cell cycle, using stained F-actin and nuclei. Scratch and transwell assays were used to determine cell migration and invasion, respectively. Gene expression was determined by quantitative Polymerase chain reaction (PCR). The most active decarboxylated extract fraction (F7) of high-cannabidiol (CBD) C. sativa was found to contain cannabichromene (CBC) and Δ9-tetrahydrocannabinol (THC). Synergistic interaction was demonstrated between CBC + THC whereas cannabinoid receptor (CB) type 1 and type 2 inverse agonists reduced cytotoxic activity. Treatments with CBC + THC or CBD led to cell cycle arrest and cell apoptosis. CBC + THC or CBD treatments inhibited cell migration and affected F-actin integrity. Identification of active plant ingredients (API) from cannabis that induce apoptosis and affect cell migration in UC cell lines forms a basis for pre-clinical trials for UC treatment.     

Spectral Properties of Effective Dynamics from Conditional Expectations

The reduction of high-dimensional systems to effective models on a smaller set of variables is an essential task in many areas of science. For stochastic dynamics governed by diffusion processes, a general procedure to find effective equations is the conditioning approach. In this paper, we are interested in the spectrum of the generator of the resulting effective dynamics, and how it compares to the spectrum of the full generator. We prove a new relative error bound in terms of the eigenfunction approximation error for reversible systems. We also present numerical examples indicating that, if Kramers–Moyal (KM) type approximations are used to compute the spectrum of the reduced generator, it seems largely insensitive to the time window used for the KM estimators. We analyze the implications of these observations for systems driven by underdamped Langevin dynamics, and show how meaningful effective dynamics can be defined in this setting.     

Oxygen-isotope labeled titania: Ti(18)O2

(18)O-isotope labelled titania (anatase, rutile) was synthesized. The products were characterized by Raman spectra together with their quantum chemical modelling. The interaction with carbon dioxide was investigated using high-resolution FTIR spectroscopy, and the oxygen isotope exchange at the Ti(18)O(2)/C(16)O(2) interface was elucidated.     

The reaction of 2,5,5-triphenyl-2-oxazolin-4-one with phosphorus pentasulfide

2,5,5-Triphenyl-2-oxazolin-4-one (3), when refluxed with phosphorus pentasulfide in xylene, is transformed into N-(3-phenyl-2-benzo[b]thienyl)-thiobenzamide (7).     

The use of 2,6-dichlorophenol-indophenol as indicator in iodometric titrations with ascorbic acid

2,6-Dichlorophenol-indophenol can be used as an indicator in iodometric methods, provided that near the end-point the solutions can be buffered with potassium hydrogen carbonate, so that ascorbic acid can be used as the titrant. Procedures for the determination of iodine, chlorine, bromine, hypochlorite, Chloramine T, bromate, iodate, permanganate, dichromate, copper(II), hydrogen peroxide, peroxydisulphate, thiosulphate, sulphite, sulphide, hydrazine and formaldehyde are described.     

Effect of pretreatment of HDS activity of supported NiW and NiMo catalysts

The hydrodesulfurization activity of sulfided NiMoO_x/Al₂O₃, NiWO_x/Al₂O₃ and NiWO_x/SiO₂−Al₂O₃ has been measured in different pretreatment conditions. Pretreatment conditions and the respective sulfur contents for optimum activities were defined.