Copolymerization of Ethylene/Diene with Different Metallocene Catalysts

2006 ◽  
Vol 61 (11) ◽  
pp. 1426-1432 ◽  
Author(s):  
Maria de Fátima Vieira Marques ◽  
Fernanda Constantino Rocha ◽  
Narda Juárez Soto
Keyword(s):  
Catalytic Activity ◽  
Thermal Properties ◽  
Reaction Time ◽  
Polymerization Rate ◽  
The Other ◽  
Copolymer Composition ◽  
Metallocene Catalysts ◽  
Ethylene Pressure ◽  
Other Hand ◽  
Catalyst Type

Copolymerizations of ethylene and 1,7-octadiene were carried out employing homogeneous catalysts Cp2ZrCl2, Ph2C(Flu,Cp)ZrCl2 and Et(Ind)2ZrCl2, and methylaluminoxane as cocatalyst. The polymerization characteristics, such as catalytic activity, polymerization rate, copolymer composition, and thermal properties were examined in relation to the catalyst type. Different comonomer concentrations were employed, and the reaction time was varied, ranging from 1 h up to 4 h, at 90°C and at 0.5 bar ethylene pressure. The results showed that the catalyst Cp2ZrCl2 was more efficient than Et(Ind)2ZrCl2 in the preparation of high diene content ethylene/1,7-octadiene copolymers. On the other hand, Et(Ind)2ZrCl2 and Ph2C(Flu,Cp)2ZrCl2 catalysts produced low insaturation content but possibly formed cyclic structures and crosslinking.

Degradation of chlorpyriphos in water by advanced oxidation processes

2010 ◽  
Vol 10 (1) ◽  
pp. 1-6 ◽  
Author(s):  
R. Murillo ◽  
J. Sarasa ◽  
M. Lanao ◽  
J. L. Ovelleiro
Keyword(s):  
Reaction Time ◽  
Light Source ◽  
Advanced Oxidation Processes ◽  
Advanced Oxidation ◽  
The Other ◽  
Molar Ratio ◽  
Optimum Conditions ◽  
Oxidation Processes ◽  
Other Hand ◽  
Initial Ph

The degradation of chlorpyriphos by different advanced oxidation processes such as photo-Fenton, TiO2, TiO2/H2O2, O3 and O3/H2O2 was investigated. The photo-Fenton and TiO2 processes were optimized using a solar chamber as light source. The optimum dosages of the photo-Fenton treatment were: [H2O2]=0.01 M; [Fe3 + ]=10 mg l−1; initial pH = 3.5. With these optimum conditions total degradation was observed after 15 minutes of reaction time. The application of sunlight was also efficient as total degradation was achieved after 60 minutes. The optimum dosage using only TiO2 as catalyst was 1,000 mg l−1, obtaining the maximum degradation at 20 minutes of reaction time. On the other hand, the addition of 0.02 M of H2O2 to a lower dosage of TiO2 (10 mg l−1) provides the same degradation. The ozonation treatment achieved complete degradation at 30 minutes of reaction time. On the other hand, it was observed that the degradation was faster by adding H2O2 (H2O2/O3 molar ratio = 0.5). In this case, total degradation was observed after 20 minutes.

CATALYTIC ACTIVITY FOR METHANE OXIDATION OF GOETHITE SUPPORTED ON ALUMINA

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4249-4254 ◽  
Author(s):  
KEI-ICHIRO MURAI ◽  
KOHEI TOMITA ◽  
SUGURU TOJO ◽  
TOSHIHIRO MORIGA ◽  
ICHIRO NAKABAYASHI
Keyword(s):  
Catalytic Activity ◽  
Specific Surface ◽  
Methane Oxidation ◽  
Model Experiment ◽  
The Other ◽  
Catalytic Activities ◽  
Surface Areas ◽  
Oxidation Of Methane ◽  
Other Hand ◽  
Specific Surface Areas

Two kinds of α- Fe 2 O 3 catalysts supported on χ- Al 2 O 3 and γ- Al 2 O 3 were synthesized. α- Fe 2 O 3 was prepared from α- FeOOH . As a model experiment, an investigation was made with the oxidation of methane. As all catalysts with various Fe contents supported on χ- Al 2 O 3 with various Fe contents had higher specific surface areas than those supported on γ- Al 2 O 3, α- Fe 2 O 3/χ- Al 2 O 3 catalyst has higher catalytic activities than α- Fe 2 O 3/γ- Al 2 O 3 catalyst. From SEM-EDS analyses, it is concluded that in α- Fe 2 O 3/χ- Al 2 O 3 catalyst, α- Fe 2 O 3 exists mainly on the surface of the support, because of flatness of the surface of χ- Al 2 O 3. On the other hand, in the case of α- Fe 2 O 3/γ- Al 2 O 3 catalyst, as the surface of support, γ- Al 2 O 3, is uneven, α- Fe 2 O 3 do not partially exist on the surface but in the pores.

Effects of Speed and Accuracy of Exertion of Force on the Relationship between Force Output and Fractionated Reaction Time

1991 ◽  
Vol 73 (1) ◽  
pp. 327-334 ◽  
Author(s):  
Shoko Kawabe-Himeno
Keyword(s):  
Reaction Time ◽  
Isometric Contraction ◽  
Light Signal ◽  
The Other ◽  
Force Output ◽  
Motor Time ◽  
Premotor Time ◽  
Other Hand ◽  
The Relationship ◽  
Speed And Accuracy

The present study was designed to investigate the effect of speed and accuracy of force exertion on the relationship between force output and fractionated reaction time. Subjects exerted their force (10% or 40% of maximum isometric contraction) on “accurate” and “fast” tasks as rapidly as possible at the light signal. On the “fast” task, premotor time for the 40% target was lengthened in comparison with that for the 10% target, and motor time was shortened with an increase of force output. On the “accurate” task, on the other hand, premotor time was independent of magnitude of force, and no relation between motor time and force output was found. These findings show that the relationship between force output and fractionated reaction time may be affected by the effort to exert force accurately.

Effects of Preparatory Period on a Reaction-Time Followed by a Pointing Movement Either Guided or Not

1973 ◽  
Vol 37 (3) ◽  
pp. 980-982
Author(s):  
Yves Guiard ◽  
Jean Requin
Keyword(s):  
Reaction Time ◽  
Movement Time ◽  
The Other ◽  
Preparatory Period ◽  
Other Hand ◽  
Pointing Movement ◽  
Pointing Task ◽  
The Mean

In a pointing task, the movement-time (MT), as opposed to reaction-time (RT), does not depend upon duration of preparatory period (PP). On the other hand, the mean MT, but not the mean RT, is shortened by guidance of the movement. The timing of preparatory processes in such task is discussed.

ZnAl2O4/Chitosan Films and Evaluation of the Influence of ZnAl2O4 Filler on the Films Morphology, Structure and Thermal Properties

2014 ◽  
Vol 775-776 ◽  
pp. 692-695
Author(s):  
Pascally M.A. Guerra de Araújo ◽  
P.T.A. Santos ◽  
Ana Cristina Figueiredo de Melo Costa ◽  
Edcleide Maria Araújo
Keyword(s):  
Thermal Stability ◽  
Thermal Properties ◽  
Flat Surface ◽  
Chitosan Film ◽  
The Other ◽  
Other Hand ◽  
Mass Proportion ◽  
Chitosan Films ◽  
Dta Curves

The present work intends to prepare ZnAl2O4/chitosan films with a mass proportion of 3:1and evaluate the influence of the ZnAl2O4 filler on the chitosan films morphology, structure and thermogravimetric properties. The films were characterized by XRD, SEM, TG and FTIR. With the XRD, it has been verified that both the chitosan and the ZnAl2O4/chitosan films presented the chitosan peaks. However, the ZnAl2O4/chitosan film also presented the ZnAl2O4 peaks. Through the SEM, it has been observed that the chitosan film presented a flat surface. On the other hand, the ZnAl2O4/chitosan presented a protruding surface. The TGA/DTA curves of the ZnAl2O4/chitosan film showed an increase in the thermal stability at temperatures greater than 720oC, comparing with the chitosan film.

Confidence-accuracy dissociation via criterion attraction

2021 ◽  
Author(s):  
Dobromir Rahnev
Keyword(s):  
Reaction Time ◽  
Recent Work ◽  
Strong Evidence ◽  
External Noise ◽  
The Other ◽  
Decision Criteria ◽  
Other Hand ◽  
Objective Performance ◽  
Multiple Tasks ◽  
Criterion Location

Humans often have to use different decision criteria in different tasks such as when detecting a mosquito against a white versus a patterned wall. However, it is debated whether people can maintain independent criteria for different tasks. Early work uncovered suboptimal biases when multiple tasks are performed simultaneously, and concluded that in such situations people inadvertently use the same decision criteria across different perceptual tasks. On the other hand, these studies could not measure the criterion location directly and more recent work has questioned whether the same criteria are indeed used across different tasks. To resolve this debate, here we develop a new external noise paradigm that can objectively quantify criterion location across two tasks that optimally require very different criteria. We find strong evidence of “criterion attraction” where the criteria across the two tasks move towards each other but do not become identical. This criterion attraction leads to a large and consistent confidence-accuracy dissociation in the absence of reaction time differences between the tasks. These results unify the seemingly disparate findings in the literature and establish a robust way of inducing dissociations between subjective and objective performance.

Research on the Application of Laccase to the Treatment of Oily Wastewater

2010 ◽  
Vol 45 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Zhi Lin Li ◽  
Wei Liu ◽  
Xin Fang Chen ◽  
He Sheng Li ◽  
Yun Miao Tian
Keyword(s):  
Reaction Time ◽  
Removal Rate ◽  
Catalytic Performance ◽  
The Other ◽  
Oily Wastewater ◽  
Oil Removal ◽  
Other Hand ◽  
Oil Concentration

Abstract The feasibility of using laccase to treat oily wastewater was examined. When only laccase was added to the synthetic oily wastewater, the suitable technological conditions were laccase at 3 U/mL, pH at 6.0, a temperature of 30°C, and a reaction time of 6 h for the initial oil concentration of 120 mg/L. Under those conditions, the rate of oil removal was as high as 69%. The effects of Mg2+, Mn2+, Cu2+, and Fe2+ ions in wastewater on the rate of oil removal using laccase were investigated. The results showed that Cu2+and Fe2+ ions obviously inhibited the catalytic performance of laccase under the studied concentration. On the other hand, Mg2+ and Mn2+ ions only had slight effects on the rate of oil removal for the range of concentrations studied. A 95% oil removal rate could be obtained when actual wastewaters were treated using laccase with the additive chitosan under the suitable technological conditions.

Natural zeolites for styrene oligomerization

Clay Minerals ◽  
2011 ◽  
Vol 46 (2) ◽  
pp. 189-195 ◽  
Author(s):  
S. Kowalak ◽  
A. Jankowska
Keyword(s):  
Catalytic Activity ◽  
High Activity ◽  
Acid Sites ◽  
The Other ◽  
Natural Zeolites ◽  
Pore Sizes ◽  
Other Hand ◽  
Synthetic Zeolites ◽  
Molecular Sizes

AbstractHydrogen forms of natural mordenite and clinoptilolite were used as catalysts for styrene oligomerization and as matrices to hold the resultant oligomers in order to prepare intense and light-resistant pigments. In contrast to synthetic zeolites of similar pore sizes (mainly H-ZSM-5, H-mordenite), the natural zeolites did not form products with an intense (pink) colouration. H-mordenite samples treated with styrene developed some colour due to styrene oligomers (the chromophore) whereas, in treated clinoptilolites, colour formation was negligible due to the lack of access of styrene molecules into the elliptical channels. The results of catalytic tests for cracking of cumene (cumene and styrene have similar molecular sizes) were consistent with the styrene oligomerization results. They indicate a noticeable catalytic activity with natural H-mordenite and a lack of activity with clinoptilolite. On the other hand, catalytic tests for propan-2-ol decomposition indicate a high activity with both natural zeolites, which confirms the presence of acid sites and their accessibility to small alcohol molecules.

scholarly journals Further evidence that the Worst Performance Rule is a special case of the Correlation of Sorted Scores Rule

2020 ◽  
Author(s):  
Kimmo Sorjonen ◽  
Guy Madison ◽  
Tomas Hemmingsson ◽  
Bo Melin ◽  
Fredrik Ullén
Keyword(s):  
Standard Deviation ◽  
Reaction Time ◽  
Large Range ◽  
Rank Order ◽  
Statistical Properties ◽  
The Other ◽  
Other Hand ◽  
Test Rank ◽  
Higher Rank ◽  
Special Case

According to the worst performance rule (WPR), the correlations between intelligence and sorted performances, for example on reaction time tasks, should strengthen from the best to the worst performance. A commonly proposed explanation for the WPR is that poor performances reflect lapses of attention that are particularly strongly related to intelligence. The correlation of sorted scores rule (CSSR), on the other hand, claims that the WPR arises due to certain statistical properties of the data. Specifically, the magnitude of intelligence-performance correlations will change with the rank order of the test when intelligence is correlated with the within-individual standard deviation (WISD) of the tests. If the latter correlation is negative, a WPR is seen, i.e. intelligence-performance correlations will be lower for tests with higher rank order. If the intelligence-WISD correlation is positive, however, intelligence-performance correlations instead increase with test rank order. In the present study, through strategic slicing of two full samples (N = 5467 and N = 43,987, respectively), we created subsamples with a large range of intelligence-WISD correlations. In accordance with the CSSR, but not the WPR, the association between intelligence-performance correlations and test rank order was found to reflect the intelligence-WISD correlation of the subsample. This indicates that the WPR might be a special case of the more general CSSR and that the WPR is crucially dependent on intelligence-WISD correlations. The findings also indicate that the predictions made by the CSSR generalize to other predictors besides intelligence and to other outcomes besides reaction time.

scholarly journals CATALYTIC ACTIVITY CoMo/USY ON DEOXYGENATION REACTION OF 4-METHOXYPHENOL IN BATCH REACTOR

2017 ◽  
Vol 13 (1) ◽  
pp. 66
Author(s):  
Khoirina Dwi Nugrahaningtyas ◽  
Irma Fadhila Putri ◽  
Eddy Heraldy
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Catalytic Activity ◽  
Reaction Time ◽  
Batch Reactor ◽  
Total Yield ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatography Mass Spectrometry ◽  
Catalyst Type

<p>This research was conducted to study the effect of catalyst type of CoMo/USY and the reaction time on the deoxygenation reaction of 4-methoxyphenol. The catalyst type used were CoMo/USY, Co-Mo/USY, and Mo-Co/USY. The product was analyzed by gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS). The activity of the Co-Mo/USY catalyst is higher than CoMo/USY and Mo-Co/USY, it can be seen from the value of total yield and the selectivity. The Co-Mo/USY catalysts shows a significant increasing on the total yield percentage (from 3.71 % to 9.41 %) during catalytic testing. The Co-Mo/USY catalyst has a highest selectivity toward 1,4-dimethoxybenzene product when the reaction time was one hour (0.92 %) and selectivity toward 1,4-dihidroxybenzene when reaction time two hours (0.43 %).</p>

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