Conversion of Polypropylene into Light Hydrocarbons and Aromatics by Metal Exchanged Zeolite Catalysts.

Polyolefins can be converted into C2-C5 hydrocarbons and benzene-toluene-xylene (BTX) aromatics as high-demand petrochemical feedstocks via catalytic pyrolysis on acidic zeolites. BroÌ·nsted and Lewis acid sites are responsible for cracking polyolefins into olefins and subsequent aromatic formation. In this study, we have subjected the parent HZSM-5 zeolite to postsynthetic partial metal exchange with Fe, Co, Ni, Cu, and Ce cations to perturb BroÌ·nsted/Lewis acidity. We have investigated these metal-modified HZSM-5 on the catalytic pyrolysis of polypropylene (PP) in a micropyrolyzer connected to a two-dimensional gas chromatograph coupled to a time-of-flight mass spectrometer and flame ionization detector (Tandem Pyrolyzer-GC × GC-TOF-MS/FID setup). Whereas Fe-, Co-, Cu-, and Ce-exchanged zeolites (with 2.5, 2.3, 1.9, and 0.8 wt % metal, respectively) had comparable product yields with the parent zeolite, Ni-exchanged zeolites with Ni content of 0.5 to 2 wt % were associated with enhanced BTX formation (28-38 wt %) compared to that of the parent zeolite (22 wt %). Pyridine-FTIR indicated that the BroÌ·nsted/Lewis acid ratio of the parent zeolite decreased upon metal ion exchange. According to Pyridine-TPD, the parent zeolite's medium-strength acid sites were redistributed into weak and strong acid sites in Ni-exchanged zeolites. The higher amount of carbon deposits on Ni-exchanged zeolites compared to the parent and other metal ion exchanged zeolites was attributed to the enhanced aromatization activity by the simultaneous decrease in the BroÌ·nsted/Lewis acid ratio and emergence of strong acid sites.

The role of spatial uncertainty in the context-specific proportion congruency effect.

The prime-probe version of the Stroop task has been predominantly used to demonstrate the context-specific proportion congruency (CSPC) effect. In this version, the location of the color is not known until its presentation, creating a spatial uncertainty for the color dimension. We propose that spatial uncertainty plays an important role in observing the CSPC effect. In this study, we investigated the role of spatial uncertainty with two experiments. In Experiment 1 (N = 53), we used a spatially separated version of the Stroop task having spatial uncertainty on the color dimension, and observed a significant CSPC effect. For Experiment 2, we conducted a preregistered prime-probe CSPC experiment with a considerably large sample (N = 128), eliminating the uncertainty of only the color dimension in one condition and both the color and the word dimensions in the other. Results showed that the CSPC effect was not observed in the first condition, while it was very small yet significant in the second condition. The Bayesian approach confirmed frequentist analyses of Experiment 1 and the first condition of Experiment 2. However, in the second condition of Experiment 2, there was no evidence regarding the existence of the CSPC effect. These findings support our claim that the spatial uncertainty of the color dimension, inherent in the prime-probe version Stroop task, contributed to the CSPC effect.

Oral Ibuprofen Versus Oral Paracetamol in Pain Management During Screening for Retinopathy of Prematurity: A Prospective Observational Study.

Screening examinations for retinopathy of prematurity (ROP) are critical to reduce ROP-related vision loss; however, the procedure is painful and uncomfortable, and topical anesthetics do not completely suppress the pain responses. The number of safe and effective pharmacological options to reduce pain during eye examinations for ROP screening in preterm infants is limited. This study compared the efficacy of oral ibuprofen and oral paracetamol in reducing pain during screening for ROP in preterm infants. This prospective observational study was conducted at a tertiary-care neonatal intensive care unit. Forty-four preterm infants with gestational age of 32 weeks and less undergoing ROP screening were included. Each enrolled infant received either oral ibuprofen 10 mg/kg (n = 22) or oral paracetamol 10 mg/kg (n = 22) 1 hour before eye examination. The primary outcome measure was pain assessed by the Neonatal Pain, Agitation, and Sedation Scale (N-PASS). Secondary outcome measures were tachycardia, bradycardia, desaturations, and crying time. The groups were similar for gestational age, birth weight, and postnatal age at examination (P > .05). The mean N-PASS scores were not significantly different between the oral ibuprofen and oral paracetamol groups (8.64 ± 1.57 vs 8.50 ± 1.71, respectively, P = .605). Moreover, no significant intergroup differences were observed in the crying time and the incidence of tachycardia/bradycardia and desaturation (P > .05). Ibuprofen or paracetamol administered orally before ROP screening in preterm infants had similar analgesic effects and did not significantly alleviate pain during eye examination.