An alternative approach for decreasing the demand and dependency for crude petroleum/bitumen binders is the use of bio-binders in three different ways: a direct alternative binder (100% replacement), a bitumen extender (25% to 75% replacement), or a bitumen modifier (<10% replacement). In this paper, the applicability of developing biobinders from switchgrass bio-oil fractions to be utilized as a direct alternative has been investigated. The results showed that the relationship between viscosity and temperature and shear rate can be well described by Arrhenius-type and Power law models, respectively, or by a log linear relationship. As an overall conclusion, the rheological properties of switchgrass bio-oils are similar and comparable to bitumen binders and represent a viable renewable alternative to petroleum derived asphalt binders.

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Most bituminous binders used for pavement materials are derived from fossil fuels, specifically crude petroleum. Nowadays, technical and economic prospects exist in using biorenewable resources to produce biobinders. Biobinders can be used in three ways to decrease the demand for crude petroleum–derived bituminous binders: direct alternative binder (100% replacement), bitumen extender (25% to 75% bitumen replacement), and bitumen modifier (<10% bitumen replacement). Applicability of developing biobinders from oakwood-based bio-oils to be used as a direct alternative has been investigated through studying the rheological properties. Temperature and shear rate (rate of loading) of biobinders and modified biobinders play major roles in changing the viscosity of bio-oils. The rheological properties of oakwood bio-oils have been investigated and compared with those of bitumen binders, to study the applicability of producing biobinders. Temperature and shear susceptibilities have been studied through measuring the viscosity of the bio-oils. Results reveal that the relationship between the viscosity of bio-oils and temperature and shear rates are log linear–like bitumen binders. In addition, temperature is the main contributor to the viscosity of the bio-oils in comparison with shear rate. Important is that the viscosity temperature susceptibility values for the bio-oils in comparison with bitumen blends indicate that bio-oils are more susceptible to temperature. Moreover, the addition of polymer modifiers leads to a change in temperature ranges of the bio-oils. In conclusion, the rheological properties of oakwood bio-oils are similar to and comparable with bitumen binders, and they represent a viable renewable alternative to petroleum-derived asphalt binders.

BackgroundCoagulation changes can complicate liver resection, particularly in patients with cirrhosis. The aim of this prospective hospital-based comparative study was to compare the postoperative analgesic efficacy of intravenous fentanyl patient-controlled analgesia (IVPCA) with and without transversus abdominis plane (TAP) block.MethodsFifty patients with Child’s A cirrhosis undergoing liver resection were randomly divided into two groups for postoperative analgesia, ie, an IVPCA group receiving a 10 μg/mL fentanyl bolus of 15 μg with a 10-minute lockout and a maximum hourly dose of 90 μg, and an IVPCA + TAP group that additionally received TAP block (15 mL of 0.375% bupivacaine) on both sides via a posterior approach with ultrasound guidance before skin incision. Postoperatively, bolus injections of bupivacaine 0.375% were given every 8 hours through a TAP catheter inserted by the surgeon in the open space during closure of the inverted L-shaped right subcostal with midline extension (subcostal approach) guided by the visual analog scale score (<3, 5 mL; 3 to <6, 10 mL; 6–10, 15–20 mL) according to weight (maximum 2 mg/kg). The top-up dosage of local anesthetic could be omitted if the patient was not in pain. Coagulation was monitored using standard coagulation tests.ResultsAge, weight, and sex were comparable between the groups (P>0.05). The visual analog scale score was significantly lower at 12, 18, 24, 48, and 72 hours (P<0.01) in IVPCA + TAP group. The Ramsay sedation score was lower only after 72 hours in the IVPCA + TAP group when compared with the IVPCA group (1.57±0.74 versus 2.2±0.41, respectively, P<0.01). Heart rate, systolic blood pressure, and fentanyl consumption were lower in the IVPCA + TAP group at 24, 48, and 72 hours (P<0.05). Intensive care unit stays were significantly shorter with TAP (2.61±0.74 days versus 4.35±0.79 days, P<0.01). Prothrombin time and International Normalized Ratio indicated temporary hypocoagulability in both groups.ConclusionCombining TAP with IVPCA improved postoperative pain management and reduced fentanyl consumption, with a shorter stay in intensive care. TAP block can be included as part of a balanced multimodal postoperative pain regimen.

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