Setting a best practice for determining the EGR rate in hydrogen internal combustion engines

Exhaust gas recirculation (EGR) is an effective way to reduce NOx-emissions and increase the efficiency of hydrogen fueled internal combustion engines. Knowledge of the exact amount of EGR is crucial to understand the effects of EGR. As the exhaust gas flow is pulsating and chemically aggressive, the flow rate is typically not measured directly and has to be derived from other quantities. For hydrocarbon fuels, the EGR rate is generally calculated from a molar CO2 balance, but for hydrogen engines this obviously cannot be used as there are no CO2 emissions, and consequently no standard practice has been established. This work considers three methods to calculate the amount of EGR in a hydrogen engine. The first one is based upon a volume balance in the mixing section of exhaust gases and fresh air. The second and third method uses a molar balance of O-2 and H2O respectively in this mixing section. The three methods are developed and tested for their accuracy with an error analysis. Additionally, the methods are applied to an experimental dataset gathered on a single cylinder hydrogen engine. Both the theoretical analysis and the experimental results confirm the method based on an O-2 molar balance as the most accurate one. The least practical method is the one based on an H2O balance as it requires additional relative humidity sensors and is less accurate than the others

Carbon Fiber Insoles Enhance Perception of Performance Despite Variable Objective Outcomes: Specific to the Moderately Active Individual

International Journal of Exercise Science 16(4): 885-897, 2023. Carbon fiber insoles (CFIs) may benefit performance in elite athletes, however, their use in moderately active individuals has been adopted without evidence supporting such enhancements in this population. Fifteen male subjects performed vertical jump (VJ) and repeat treadmill sprint tests before and after a VO2peak while wearing 1) CFIs and 2) control insoles (CON). Subjects completed a subjective survey regarding their perceived performance abilities for both conditions. There were no significant differences between CFIs and CON in VJ height, sprint distance, heart rate following sprints; and rate of oxygen consumption, perceived fatigue, and perceived exertion at 85% of maximal speed (p \u3e 0.05) during the VO2peak. At maximal speed, although there was no difference between conditions in peak rate of oxygen consumption (95%CI [-4.85, 0.21]) and respiratory exchange ratio (95%CI [-0.01, 0.03]), CFIs resulted in a reduced level of perceived fatigue (95%CI [-1, 0]) and perceived exertion (95%CI [-2, 0]) compared to CON. Subjects subjectively reported increased feelings of “propulsion or explosiveness” (p = 0.026) and being able to “perform better while jumping” (p = 0.029) while wearing CFIs. Heightened perceptions of performance enhancements when wearing CFIs indicate, in the moderately active, perceptual benefits could be more influential for determining CFI use

Performances of Solid Oxide Cells with La0.97_{0.97}Ni0.5_{0.5}Co0.5_{0.5}O3−δ_{3-\delta} as Air-Electrodes

Based on previous studies of perovskites in the quasi-ternary system LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$, La$_{0.97}$Ni$_{0.5}$Co$_{0.5}$O$_{3}$ (LNC) is chosen as the most promising air-electrode material in the series for solid oxide cells (SOCs). The properties of the material itself have been investigated in detail. However, the evaluation of LNC97 air electrodes in practical SOCs is still at a very early stage. In the present study, SOCs were prepared based on LNC97 air electrodes. The I-U performance of the SOCs in both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC) modes, i.e. reversible SOCs (r-SOCs), was investigated systematically for different air-electrode designs, temperatures and fuel gases. In general, the performance of the r-SOCs tested in the present study is higher than the published results of other LaFeO$_{3}$–LaCoO$_{3}$–LaNiO$_{3}$-based SOCs and is comparable to or even better than state-of-the-art La$_{1-x}$Sr$_{x}$Fe$_{1-y}$Co$_{y}$O$_{3}$ (LSCF)-based SOCs. Mid-term operation of about 1000 h for SOCs in both SOFC and SOEC modes primarily proved the stability of LNC97-based air electrodes. Impedance spectra were systematically applied to understand the polarization processes of the SOCs

Intentional replantation for the management of maxillary sinusitis

Aim. To present a case that emphasizes the importance of the use of intentional replantation as a technique to successfully treat a periapical lesion and an odontogenic maxillary sinusitis through the alveolus at the same time. Summary. This case report presents a patient with odontogenic maxillary sinusitis secondary to periapical disease of a maxillary molar that had previously received root canal treatment. The molar was extracted, with drainage and rinsing of the maxillary sinus. The apices were resected extra-orally, and the retrograde cavity was prepared with ultrasound and retrograde filling using silver amalgam. The tooth was then replanted. After 2 years, the patient was asymptomatic, periapical radiography showed no evidence of root resorption and computed tomography scanning demonstrated the resolution of maxillary sinusitis

Kinematics of Stellar Populations with RAVE Data

We study the kinematics of the Galactic thin and thick disk populations using stars from the RAVE survey's second data release together with distance estimates from Breddels et al. (2009). The velocity distribution exhibits the expected moving groups present in the solar neighborhood. We separate thick and thin disk stars by applying the X (stellar-population) criterion of Schuster et al. (1993), which takes into account both kinematic and metallicity information. For 1906 thin disk and 110 thick disk stars classified in this way, we find a vertical velocity dispersion, mean rotational velocity and mean orbital eccentricity of (sigma_W, Vphi, e)_thin = (18\pm0.3 km/s, 223\pm0.4 km/s, 0.07\pm0.07) and (sigma_W, Vphi, e)_thick = (35\pm2 km/s, 163\pm2 km/s, 0.31\pm0.16), respectively. From the radial Jeans equation, we derive a thick disk scale length in the range 1.5-2.2 kpc, whose greatest uncertainty lies in the adopted form of the underlying potential. The shape of the orbital eccentricity distribution indicates that the thick disk stars in our sample most likely formed in situ with minor gas-rich mergers and/or radial migration being the most likely cause for their orbits. We further obtain mean metal abundances of _thin = +0.03 \pm 0.17, and _thick = -0.51\pm0.23, in good agreement with previous estimates. We estimate a radial metallicity gradient in the thin disk of -0.07 dex/kpc, which is larger than predicted by chemical evolution models where the disk grows insideout from infalling gas. It is, however, consistent with models where significant migration of stars shapes the chemical signature of the disk, implying that radial migration might play at least part of a role in the thick disk's formation.Comment: 27 pages, 7 figures, accepted for publication in New Astronom

Genetic diversity, demographic history and neo-sex chromosomes in the Critically Endangered Raso lark

Small effective population sizes could expose island species to inbreeding and loss of genetic variation. Here, we investigate factors shaping genetic diversity in the Raso lark, which has been restricted to a single islet for approximately 500 years, with a population size of a few hundred. We assembled a reference genome for the related Eurasian skylark and then assessed diversity and demographic history using RAD-seq data (75 samples from Raso larks and two related mainland species). We first identify broad tracts of suppressed recombination in females, indicating enlarged neo-sex chromosomes. We then show that genetic diversity across autosomes in the Raso lark is lower than in its mainland relatives, but inconsistent with long-term persistence at its current population size. Finally, we find that genetic signatures of the recent population contraction are overshadowed by an ancient expansion and persistence of a very large population until the human settlement of Cape Verde. Our findings show how genome-wide approaches to study endangered species can help avoid confounding effects of genome architecture on diversity estimates, and how present-day diversity can be shaped by ancient demographic events

Men and infertility in The Gambia : limited biomedical knowledge and awareness discourage male involvement and exacerbate gender-based impacts of infertility

Introduction Infertility in Sub-Saharan Africa constitutes an important social and public health problem. Yet, there is a paucity of research on the experiences of men living with infertility, especially in West Africa. This study explored men’s aetiological knowledge, views and experiences of infertility in the West Coast region of The Gambia, West Africa. Methodology An explorative qualitative study was conducted among men living in the rural and urban communities of the West Coast region of The Gambia using in-depth interviews. Data collection and analysis were performed concurrently, and thematic data analysis was an iterative process carried out using NVivo 11 Analysis Software. Results Gambian men had generally poor knowledge of infertility, allocating it to God, spiritual powers and bodily (biomedical) factors. While societal norms meant that infertility was generally attributed to women, some men allocated male-factor infertility to poor sperm quality and impotence. Infertility threatened participants’ sense of masculinity and resulted in psychosocial distress, including stigma, feelings of isolation, and low self-esteem. Conclusion Normative gendered frameworks of infertility result in high levels of female responsibilisation in the Gambian context. Yet men diagnosed with infertility experience significant, often unrecognized, psychological and social distress. We therefore call for increased attention to male-factor infertility, and the promotion of male engagement with infertility-care and services, both of which are essential for successfully addressing infertility and it’s psychosocial consequences in The Gambia