Multi-criteria decision analysis for the evaluation and screening of sustainable aviation fuel production pathways

The aviation sector, a significant greenhouse gas emitter, must lower its emissions to alleviate the climate change impact. Decarbonization can be achieved by converting low-carbon feedstock to sustainable aviation fuel (SAF). This study reviews SAF production pathways like hydroprocessed esters and fatty acids (HEFA), gasification and Fischer–Tropsch Process (GFT), Alcohol to Jet (ATJ), direct sugar to hydrocarbon (DSHC), and fast pyrolysis (FP). Each pathway's advantages, limitations, cost-effectiveness, and environmental impact are detailed, with reaction pathways, feedstock, and catalyst requirements. A multi-criteria decision framework (MCDS) was used to rank the most promising SAF production pathways. The results show the performance ranking order as HEFA > DSHC > FP > ATJ > GFT, assuming equal weight for all criteria

Physical Activity Level and Adiposity: Are they Associated with Primary Dysmenorrhea in School Adolescents?

Information on self-reported physical activity (PA) level in association with primary dysmenorrhea (PD) is not readily available on African populations, and there is a dearth of information on the association of adiposity with PD. This study explored the association of PA and adiposity indices with PD and associated menstrual pain. This cross-sectional study involved 1383 female adolescents from 12 randomly selected secondary schools (9 private and 3 public schools). They were categorized into <1 hour/day or ≥ 1 hour/day of PA based on their reported average duration of PA per day. The adiposity [body mass index (BMI) and waist circumference (WC)] was assessed using standardized procedures. Majority of participants (85.4%) in this study sample reported experiencing PD. More participants without PD engaged in PA for more than one hour daily than those with PD (X2=11.49; p=0.001). The participants with PD experienced menstrual pain mostly (55.1%) during menstruation and the mostly reported pain intensity was moderate (38.7%). Majority of those (80.5%) who had menstrual pain did not report using medication for the pain. 77.0% of those who used medication reported having pain relief. Waist circumference, BMI and PA level showed no independent association (p>0.05) with either PD or its pain intensity experienced among the adolescents. PA level and adiposity are not associated with PD in school adolescents. Keywords: Adiposity, Primary Dysmenorrhea, Physical Activity, Adolescence (Afr J Reprod Health 2013; 17[4]: 167-174

Physical Activity Level and Adiposity: Are they Associated with Primary Dysmenorrhea in School Adolescents?

Information on self-reported physical activity (PA) level in association with primary dysmenorrhea (PD) is not readily available on African populations, and there is a dearth of information on the association of adiposity with PD. This study explored the association of PA and adiposity indices with PD and associated menstrual pain. This cross-sectional study involved 1383 female adolescents from 12 randomly selected secondary schools (9 private and 3 public schools). They were categorized into <1 hour/day or ≥ 1 hour/day of PA based on their reported average duration of PA per day. The adiposity [body mass index (BMI) and waist circumference (WC)] was assessed using standardized procedures. Majority of participants (85.4%) in this study sample reported experiencing PD. More participants without PD engaged in PA for more than one hour daily than those with PD (X2=11.49; p=0.001). The participants with PD experienced menstrual pain mostly (55.1%) during menstruation and the mostly reported pain intensity was moderate (38.7%). Majority of those (80.5%) who had menstrual pain did not report using medication for the pain. 77.0% of those who used medication reported having pain relief. Waist circumference, BMI and PA level showed no independent association (p>0.05) with either PD or its pain intensity experienced among the adolescents. PA level and adiposity are not associated with PD in school adolescents.Les informations sur le niveau d&apos;activité physique auto-déclarée (AP) en association avec la dysménorrhée primaire (DP) par rapport aux populations africaines ne sont pas facilement disponibles et il y a un manque d&apos;informations sur l&apos;association de l&apos;adiposité avec la DP. Cette étude a exploré l&apos;association de l’AP et des indices d&apos;adiposité avec la DP et les douleurs menstruelles associées. Cette étude transversale a impliqué 1 383 adolescentes de 12 écoles secondaires choisies au hasard (9 écoles publiques, et 3 écoles privées). EIles ont été classées en < 1 heure / jour ou ≥ 1 heure / jour de AP en fonction de leur durée moyenne déclarée de AP par jour. L&apos;adiposité [indice de masse corporelle (IMC) et le tour de taille (TT) ] ont été évalués à l’aide des procédures standardisées. La majorité des participants (85,4%) de l&apos;échantillon de l&apos;étude ont déclaré avoir subi la DP. Plus de participants sans DP étaient engagés dans la AD pendant plus d&apos;une heure par jour que ceux DP (X2 = 11,49, p = 0,001). Les participants DP ont connu surtout les douleurs menstruelles (55,1%) pendant la menstruation et l&apos;intensité de la douleur souvent rapporté a été modérée ( 38,7%) . La majorité d&apos;entre elle (0,5%) qui ont eu la douleur menstruelle n&apos;ont pas signalé l&apos;utilisation de médicaments contre la douleur. 77,0% de ceux qui ont utilisé des médicaments ont déclaré avoir été soulagées. Le tour de taille, l&apos;IMC et le niveau d’AP n’ont pas montré une association (p > 0,05) avec soit la DP soit son intensité de douleur ressentie chez les adolescents. Le niveau d&apos;AP et de l’adiposité ne sont pas associés à la DP chez les adolescents qui fréquentent école

Biomethane and propylene glycol synthesis via a novel integrated catalytic transfer hydrogenolysis, carbon capture and biomethanation process

A novel conceptual design for the co-production of biomethane and propylene glycol from integrated catalytic transfer hydrogenolysis (CTH), biogenic CO2 capture and biomethanation reaction was presented in this study. Furthermore, process economics and environmental impact study was performed to appraise the feasibility of the proposed design. The minimum selling price (MSP) of propylene glycol produced considering the overall cost of biomethane as co-product is 1.41 U.S.$/kg. However, if the cost of biomethane was not considered or if the biomethane produced is not enough to yield a yearly revenue then the MSP would increase to 1.43 U.S.$/kg. The MSP of biomethane for the integrated process was 148 U.S.$/MWh. The MSPs of propylene glycol and biomethane were comparable with those of the business-as-usual technology. Factors such as hydrogen donor solvent cost, catalyst cost, electricity price and equipment purchase cost influenced the MSP. Environmental assessment studies showed that the standalone CTH had a higher overall carbon footprint (carbon emissions of 3.7 MM tonnes/yr.). This could be attributed to the consumption of CO2 derived from the process streams via biomethanation process

Anaerobic co-digestion of food waste and agricultural residues:an overview of feedstock properties and the impact of biochar addition

Large amount of food and agricultural residues are discharged as municipal wastes. These biogenic waste possess high sugar content and are being dumped into landfills or incinerated, creating severe environmental challenges. Anaerobic co-digestion (AcD) of food waste and agricultural residues provides a sustainable valorisation route for biogas production. Biochar addition promotes the microbial activity, electrical conductivity, and molar interactions in the anaerobic digester. The present review presents an overview of the influence of biochar on the product yield during AcD. An overview of different classification of food waste and agricultural residues is presented. In addition, studies related to the application of biochar to enhance AcD were critically reviewed as well as the future outlook. The conducted studies revealed that the addition of biochar to AcD process can mitigate the buffering capacity and toxic process inhibitors faced in AcD, and ultimately enhance biogas yields, shortening the lag-phase and biodegrading running time. Biochar has a unique surface functional groups that can be modified by functionalization or by adjusting the pyrolysis temperature for optimal efficiency of specific co-substrate combinations of feedstocks. In AcD process, engineered biochar can be directed to specifically adsorb precise indirect (limonene) or direct (NH3, CO2) inhibitors for optimal process efficiency and methane production based on active surface functional groups, alkalinity of the material and hydrophobicity. Hence, biochar enhanced with the right pore sizing and pH can offset AcD limitations and improve process efficiency. The presented review provide an in- depth understand on the influence of biochar on product yield during AcD process

Multi-criteria decision analysis for the evaluation and screening of sustainable aviation fuel production pathways

&lt;p&gt;The aviation sector, a significant greenhouse gas emitter, must lower its emissions to alleviate the climate change impact. Decarbonization can be achieved by converting low-carbon feedstock to sustainable aviation fuel (SAF). This study reviews SAF production pathways like hydroprocessed esters and fatty acids (HEFA), gasification and Fischer&ndash;Tropsch Process (GFT), Alcohol to Jet (ATJ), direct sugar to hydrocarbon (DSHC), and fast pyrolysis (FP). Each pathway&rsquo;s advantages, limitations, cost-effectiveness, and environmental impact are detailed, with reaction pathways, feedstock, and catalyst requirements. A multi-criteria decision framework (MCDS) was used to rank the most promising SAF production pathways. The results show the performance ranking order as HEFA &gt; DSHC &gt; FP &gt; ATJ &gt; GFT, assuming equal weight for all criteria.&lt;/p&gt

Process design, exergy, and economic assessment of a conceptual mobile autothermal methane pyrolysis unit for onsite hydrogen production

The present study proposes a conceptual mobile autothermal methane pyrolysis unit for onsite hydrogen production. Considering the shortage of hydrogen pipeline infrastructure between production plants and fuelling stations in most places where hydrogen is required, it is imperative to create alternative hydrogen production means. The design combines a catalytic plasma methane pyrolysis unit with a steam char gasification setup, combustion, and biomethanation unit for hydrogen production. The reactor design includes Ni - Br in a bubble column acting as a catalyst. Energy and exergy calculations followed by a comprehensive economic analysis were appraised to evaluate the efficiency and performance of the integrated process. The levelized cost of hydrogen (LCOH) from the conceptual design ranged from 1.3 to 1.47 U.S.$/kg, while the proposed design's net present value (NPV) was in the range of 3.76 – 4.35 M.U.S.$. Factors such as equipment purchase cost (EPC) and feedstock cost significantly influenced the NPV and LCOH. In addition, a positive NPV and lower LCOH outline the proposed design's profitability. Finally, an optimized methane conversion of 76.8 % was obtained from the study

Potential for false-positive HIV test results using rapid HIV testing algorithms

Background: In order to scale up access to HIV counselling and testing in Nigeria, an HIV diagnostic algorithm based on rapid testing was adopted. However, there was the need to further evaluate the testing strategy in order to better assess its performance, because of the potential for false positivity. Objectives: The objective of this study was to compare positive HIV test results obtained from the approved rapid testing algorithm with results from western blot tests performed on samples from the same patient. Methodology: A retrospective review was conducted of HIV screening and confirmatory results for patients seen between 2007 and 2008. Rapid test and western blot results were extracted and compared for concordance. Discordant results were further reviewed using a combination of HIV-1 RNA viral load and CD4+ cell count test results and clinical presentation from medical records. Results: Analysis of 2228 western blot results showed that 98.3% (n = 2191) were positive for HIV-1, 0.4% (n = 8) were positive for HIV-2 and 0.3% (n = 7) were dual infections (positive for both HIV-1 and HIV-2); 0.6% (n = 13) were indeterminate and 0.4% (n = 9) were negative. Further investigation of the 13 indeterminate results showed nine to be HIV-1 positive and four to be HIV-negative, for a total of 13 negative results. The positive predictive value of the HIV counselling and testing algorithm was 99.4%. Conclusion: Using the rapid testing algorithm alone, false positives were detected. Therefore, effective measures such as training and retraining of staff should be prioritised in order to minimise false-positive diagnoses and the associated potential for long-term psychological and financial impact on the patients

Proficiency testing for HIV, tuberculosis and malaria diagnosis in clinical laboratories in Nigeria

Background: Proficiency testing (PT) is a means of verifying the reliability of laboratory results, but such programmes are not readily available to laboratories in developing countries. This project provided PT to laboratories in Nigeria. Objectives: To assess the proficiency of laboratories in the diagnosis of HIV, tuberculosis and malaria. Methods: This was a prospective study carried out between 2009 and 2011. A structured questionnaire was administered to 106 randomly-selected laboratories. Forty-four indicated their interest in participation and were enrolled. Four rounds of pre-characterised plasma panels for HIV, sputum films for tuberculosis and blood films for malaria were distributed quarterly by courier over the course of one year. The results were returned within two weeks and scores of ≥ 80% were reported as satisfactory. Mentoring was offered after the first and second PT rounds. Results: Average HIV PT scores increased from 74% to 95% from the first round to the third round, but decreased in the fourth round. For diagnosis of tuberculosis, average scores increased from 42% in the first round to 78% in the second round; but a decrease to 34% was observed in the fourth round. Malaria PT performance was 2% at first, but average scores increased between the second and fourth rounds, culminating in a fourth-round score of 39%. Many participants requested training and mentoring. Conclusions: There were gross deficiencies in the quality of laboratory services rendered across Nigeria. In-country PT programmes, implemented in conjunction with mentoring, will improve coverage and diagnosis of HIV, tuberculosis and malaria