Plastics to fuel or plastics: Life cycle assessment-based evaluation of different options for pyrolysis at end-of-life.

Pyrolysis is a leading technology to convert non-recyclable plastic waste to fuels or chemicals. As interest in the circular economy grows, the latter option has seemingly become more attractive. Once waste plastic is pyrolyzed to, for example, naphtha, however, additional steps are required to produce a polymer product. These steps consume additional energy and water and emit greenhouse gases (GHG). It is unclear whether this more circular option of non-recyclable plastics to virgin plastics offers environmental benefits, compared to their conversion to fuels. We therefore examine whether it is possible to determine the best use of pyrolyzing non-recyclable plastic - fuels or chemicals (low-density polyethylene (LDPE) as product)- from a life cycle perspective. We use recently published life cycle assessments of non-recycled plastics pyrolysis and consider two functional units: per unit mass of non-recyclable plastics and per unit product - MJ of naphtha or kg of LDPE. In the U.S., on a cradle-to-gate, per unit mass waste basis, producing fuel is lower-emitting than producing LDPE from pyrolysis. The opposite is true in the EU. But expanding the system boundary to the grave results in LDPE as the lower-emitting product in both regions. Naphtha and LDPE produced from non-recyclable plastics are less GHG-intensive than conventional routes to these products. Fossil fuel and water consumption and waste generation are all lower in the P2F case. Our results highlight that prioritization of P2P and P2F may depend on regional characteristics such as conventional waste management techniques and water scarcity.

Bispectral index score and observer's assessment of awareness/sedation score may manifest divergence during onset of sedation: Study with midazolam and propofol.

BACKGROUND: Correlation between the clinical and electroencephalogram-based monitoring has been documented sporadically during the onset of sedation. Propofol and midazolam have been studied individually using the observer's assessment of awareness/sedation (OAA/S) score and Bispectral index score (BIS). The present study was designed to compare the time to onset of sedation for propofol and midazolam using both BIS and OAA/S scores, and to find out any correlation. METHODS: A total of 46 patients (18-60 years, either sex, American Society of Anesthesiologists (ASA) I/II) posted for infraumbilical surgeries under spinal anaesthesia were randomly allocated to receive either injection propofol 1 mg/kg bolus followed by infusion 3 mg/kg/h (Group P, n=23) or injection midazolam 0.05 mg/kg bolus followed by infusion 0.06 mg/kg/h (Group M, n=23). Spinal anaesthesia was given with 2.5 ml to 3.0 ml of 0.5% bupivacaine heavy. When sensory block reached T6 level, sedation was initiated. The time to reach BIS score 70 and time to achieve OAA/S score 3 from the start of study drug were noted. OAA/S score at BIS score 70 was noted. Data from 43 patients were analyzed using SPSS 12 for Windows. RESULTS: Time to reach BIS score 70 using propofol was significantly lower than using the midazolam (P<0.05). Time to achieve OAA/S score 3 using propofol was comparable with midazolam (P=0.358). CONCLUSION: A divergence exists between the time to reach BIS score 70 and time to achieve OAA/S score 3 using midazolam, compared with propofol, during the onset of sedation.

Codon and amino acid usage in two major human pathogens of genus Bartonella--optimization between replicational-transcriptional selection, translational control and cost minimization.

Intra-genomic variation in synonymous codon and amino acid usage in two human pathogens Bartonella henselae and B. quintana has been carried out through multivariate analysis. Asymmetric mutational bias, coupled with replicational-transcriptional selection, has been identified as the prime selection force behind synonymous codon selection--a characteristic of the genus Bartonella, not exhibited by any other alpha-proteobacterial genome. Distinct codon usage patterns and low synonymous divergence values between orthologous sequences of highly expressed genes from the two Bartonella species indicate that there exists a residual intra-strand synonymous codon bias in the highly expressed genes, possibly operating at the level of translation. In the case of amino acid usage, the mean hydropathy level and aromaticity are the major sources of variation, both having nearly equal impact, while strand-specific mutational pressure and gene expressivity strongly influence the inter-strand variations. In both species under study, the highly expressed gene products tend not to contain heavy and/or aromatic residues, following the cost-minimization hypothesis in spite of their intracellular lifestyle. The codon and amino acid usage in these two human pathogens are, therefore, consequences of a complex balance between replicational-transcriptional selection, translational control, protein hydropathy and cost minimization.