Mesoporous superacid catalysts for valorisation of refinery naphtha stream

In the current petroleum refining scenario, many refineries end up with surplus naphtha which is either absorbed into the gasoline pool or exported at unattractive prices. Therefore, several options for naphtha valorisation are currently being explored. The usage of Liquified Petroleum Gas (LPG) as a fuel in heating appliances, cooking equipment and automobiles is rapidly increasing. The high specific calorific value, high octane number, clean and efficient combustion of LPG distinguish it as an extremely promising fuel of the future. In the current work, tungstophosphoric acid (TPA) supported on four different mesoporous silica supports were investigated as mesoporous superacids for hydroconversion of refinery naphtha using n-heptane as a model feedstock. The varied levels of interactions of prepared mesoporous silica with tungstophosphoric acid catalysts were observed to have a prominent effect on the strength of the acid sites generated on silica surfaces and as a result affected heptane hydroconversion activity and selectivity of isomerized and cracked products. Interestingly, activity could be tuned towards selective cracking or isomerization-cracking by selection of a suitable topology of mesoporous silica. Hexagonal Mesoporous Silica (HMS) and plugged SBA-15 supported TPA catalysts demonstrated high n-heptane conversion activity and isomerization selectivity whereas KIT-6 and SBA-15 supported TPA catalysts demonstrated high cracking selectivity to LPG.

TPA silanol interactions in mesoporous TPA silica composites govern the strength of acid sites, activity and selectivity.     

Opioid versus non-opioid analgesia for spine surgery: a systematic review and meta-analysis of randomized controlled trials

Purpose

Opioids are the primary analgesics used in patients undergoing spine surgery. Postoperative pain is common despite their liberal use and so are opioid-associated side effects. Non-opioid analgesics are gaining popularity as alternative to opioids in spine surgery.

Methods

This systematic review evaluated current evidence regarding opioid and non-opioid intraoperative analgesia and their influence on immediate postoperative pain and adverse events in spine surgery.

Results

A total of 10,459 records were obtained by searching Medline, EMBASE and Web of Science databases and six randomized controlled trials were included. Differences in postoperative pain scores between opioid and non-opioid groups were not significant at 1 h: 4 studies, mean difference (MD) = 0.65 units, 95% confidence intervals (CI) [−0.12 to 1.41], p = 0.10, but favored non-opioid at 24 h after surgery: 3 studies, MD = 0.75 units, 95%CI [0.03 to 1.46], p = 0.04. The time for first postoperative analgesic requirement was shorter (MD = −45.06 min, 95%CI [−72.50 to −17.62], p = 0.001), and morphine consumption during first 24 h after surgery was higher in opioid compared to non-opioid group (MD = 4.54 mg, 95%CI [3.26 to 5.82], p < 0.00001). Adverse effects of postoperative nausea and vomiting (Relative risk (RR) = 2.15, 95%CI [1.37 to 3.38], p = 0.0009) and shivering (RR = 2.52, 95%CI [1.08 to 5.89], p = 0.03) were higher and bradycardia was lower (RR = 0.35, 95%CI [0.17 to 0.71], p = 0.004) with opioid analgesia.

Conclusion

The certainty of evidence on GRADE assessment is low for studied outcomes. Available evidence supports intraoperative non-opioid analgesia for overall postoperative pain outcomes in spine surgery. More research is needed to find the best drug combination and dosing regimen.

Prospero Registration: CRD42020209042.

     

Congenital inferior sinus venosus defect associated with pulmonary valve stenosis: A late presentation of a rare disease

Congenital inferior sinus venosus defect (SVD) is a rare congenital heart disease. Proper diagnosis of this disease is challenging and requires understanding of cardiac hemodynamics. Here, we discuss a patient with a late presentation of combined congenital inferior SVD associated with congenital pulmonary stenosis.