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Higher Plasma Levels of Valerate Produced by Gut Microbiota May Have a Beneficial Impact on Renal Function
No full textObjective: Observational studies have evaluated the relationships among plasma short chain fatty acids (SCFA) produced by gut microbiota, renal function, and risk of chronic kidney disease (CKD). In the present study, Mendelian Randomization (MR) analysis was applied to obtain unconfounded estimates of the casual association of genetically determined plasma valerate (an SCFA) with kidney function and risk of CKD. Method: MR was performed by using summary-level data from the largest genome-wide association studies (GWAS) conducted on plasma valerate, CKD, and estimated glomerular filtration rate (eGFR; separately in diabetic and nondiabetic individuals). Inverse variance weighted method (IVW), weighted median–based method, MR-Egger, as well as MR-Pleiotropy RESidual Sum and Outlier (PRESSO) were applied. Sensitivity analysis was conducted using the leave-one-out method. Results: No significant association was observed between plasma valerate and CKD (IVW: β = 0.234, p = 0.744). In contrast, plasma valerate was positively associated with eGFR in the total population (IVW: β = 0.049, p = 0.022) and among nondiabetic individuals (IVW: β = 0.058, p = 0.009), but not in the diabetic population (IVW: β = −0.052, p = 0.603). None of the estimated associations was subjected to significant level of heterogeneity. Furthermore, MR-PRESSO analysis did not show any chance of outlier for all estimates. The pleiotropy test, with very a negligible intercept and insignificant p value, also indicated no chance of pleiotropy for all of our estimations (all p > 0.539). The results of the MR-Robust Adjusted Profile Score were identical with the IVW estimates, highlighting again no possibility of pleiotropy. Results of the leave-one-out method demonstrated that the links were not driven by single-nucleotide polymorphisms. Conclusions: Individuals with higher plasma valerate levels had better renal function, defined by eGFR. This finding was observed in the total population and in nondiabetic subjects, but not in those with diabetes. Further research is needed to elucidate the links among plasma valerate, kidney function, and CKD
Resource efficiency factors in industrialised construction-a study in developing economies
Get PDFDeveloping economies need to supply housing and ensure resource efficiency in the process. Industrialised construction, which increases productivity in construction, can be one means to deliver the needed housing. However, the resource efficiency of industrialised construction in developing economies is under-researched. This paper studies factors influencing resource efficiency in industrialised housing products from a perspective of value chain and environmental impact in Addis Ababa, Ethiopia; Nairobi, Kenya; and Cape Town, South Africa. Specifically, wall systems with varying degrees of industrialised construction implementation are studied. The study uncovers four main insights - first, the choice of materials influences the resource-efficiency of industrialised wall systems. However, the current value chain does not promote the adoption of new materials. Second, products used for industrialised wall systems are imported and incur added transportation-related impacts and beyond. Third, industrialised construction wall systems often use lightweight materials and have the potential for disassembly. However, end-users have reservations about such design strategies. Fourth, controlled production of wall systems reduces construction waste and increases the quality of products. Nevertheless, governments are currently promoting labour-intensive construction methods. Based on these insights, the paper concludes with recommendations, levers, and action points for stakeholders to promote resource efficiency in industrialised construction adoption
Direct measurements and CFD simulations on ice-induced hull pressure of a ship in floe ice fields
No full textFloe ice fields are expected to replace level ice to be the most common environment for future polar sea transportation under the long-term trend of global warming. In this study, the authors aim to develop a viable analysis procedure to predict the ice-induced hull pressure characteristics for ships navigating in floe ice fields. A novel ice model test procedure is established, which is characterized by making use of non-refrigerated synthetic model ice and tactile pressure sensors to measure the hull pressure. The numerical tool is based on a state-of-the-art CFD-DEM numerical framework; a novel method to monitor the hull pressure during the interaction between the hull and ice floes during the CFD-DEM simulations. Statistical analysis indicates the probability distributions of the ice pressure from the experiment and the numerical results are comparable. Besides, the impacts of ship speed and ice floe concentration on the hull pressure distribution are also examined. Increasing speed and ice concentration will make the probability distribution of ice pressure shift towards the high-pressure going interval, resulting in an increased mean of ice pressure. It is also found that increased speed leads to a smaller variance, while increased ice concentration results in a larger variance
Discovery of Hydrogen Radio Recombination Lines at z = 0.89 toward PKS 1830-211
Get PDFWe report the detection of stimulated hydrogen radio recombination line (RRL) emission from ionized gas in a z = 0.89 galaxy using 580-1670 MHz observations from the MeerKAT Absorption Line Survey. The RRL emission originates in a galaxy that intercepts and strongly lenses the radio blazar PKS 1830−211 (z = 2.5). This is the second detection of RRLs outside of the local Universe and the first clearly associated with hydrogen. We detect effective H144α (and H163α) transitions at observed frequencies of 1156 (798) MHz by stacking 17 (27) RRLs with 21σ (14σ) significance. The RRL emission contains two main velocity components and is coincident in velocity with H i 21 cm and OH 18 cm absorption. We use the RRL spectral line energy distribution and a Bayesian analysis to constrain the density (n e ) and the volume-averaged path length (ℓ) of the ionized gas. We determine log ( n e ) = 2.0 − 0.7 + 1.0 cm−3 and log ( ℓ ) = − 0.7 − 1.1 + 1.1 pc toward the northeast (NE) lensed image, likely tracing the diffuse thermal phase of the ionized ISM in a thin disk. Toward the southwest (SW) lensed image, we determine log ( n e ) = 3.2 − 1.0 + 0.4 cm−3 and log ( ℓ ) = − 2.7 − 0.2 + 1.8 pc, tracing gas that is more reminiscent of H scii regions. We estimate a star formation (surface density) rate of ΣSFR ∼ 0.6 M ⊙ yr−1 kpc−2 or SFR ∼ 50 M ⊙ yr−1, consistent with a star-forming main-sequence galaxy of M ⋆ ∼ 1011 M ⊙. The discovery presented here opens up the possibility of studying ionized gas at high redshifts using RRL observations from current and future (e.g., SKA and ngVLA) radio facilities
Study of bio-oil and bio-char production from thermal and catalytic hydrotreatment of simulated pyrolysis oil under mild conditions
Get PDFPyrolysis oil derived from fast pyrolysis of lignocellulosic biomass is a promising alternative energysource used to produce renewable biofuels. However, the high reactivity of unsaturated oxygenatedcompounds in pyrolysis oil results in charring and deactivation of the catalyst under severehydrotreatment conditions. This thesis focuses on reactions during stabilization of such oils, specifically,the undesirable carbon loss to solid char as the main side reaction.In the first study, mild thermal and catalytic hydrotreatment of a simulated pyrolysis oil, containing acomprehensive mixture of various oxygenated groups, was performed using NiMo/Al2O3 under mildconditions of 180-300\ub0C and 60 bar hydrogen in a batch reactor. The solid products were extracted intosoluble and insoluble solid fractions to determine the degree of polymerization. It was found that thesoluble solids transformed into the bio-liquid product and solid insoluble yield was suppressed atelevated temperatures. It was also accompanied by a higher degree of hydrodeoxygenation (HDO)causing the stabilization of light oxygenates, and a significant decrease in the formation of heavyoligomers in the liquid phase. In catalyst-free experiments, the formation of solids was higher andshowed a decreasing trend when increasing the temperature, except during heating where no solids wereobserved for the non-catalytic experiment. In the presence of the catalyst, the soluble solids at lowertemperatures (180\ub0C) consisted of macromolecule structures that were rich in sugar derivatives, whilethe corresponding insoluble solids were not fully developed into char. Their composition changed toaliphatic compounds and fully developed char respectively at higher temperatures. Moreover, theremoval of furan and sugar compounds was found to be crucial to reduce the solid char formation.In the second study, a set of catalysts; Pt/Al2O3, Rh/Al2O3, Pd/Al2O3, Re/Al2O3, and NiMo-S/Al2O3 wasused to stabilize the same simulated pyrolysis oil at identical reaction conditions (180\ub0C) as applied inthe first study. The catalyst screening results showed that Pd/Al2O3 was significantly better in terms ofachieving the highest conversion of pyrolysis oil and producing a high yield (66 wt%) of liquid oilproduct. The bio-liquid was mostly composed of low molecular weight compounds such as stabilizedoxygenates and hydrocarbons. It also featured a minimum solid formation (3.3 wt%) in which solublepolymers were more pronounced. The results also indicated that NiMo-S/Al2O3 was fairly good incatalyzing reactive compounds, except furans, into stable light oxygenates with the formed solids richin heavy insoluble polymers (13.6 wt%). The Rh/Al2O3 was comparable to NiMo-S/Al2O3, however,Pt/Al2O3 and particularly Re/Al2O3 rendered poor performances with the lowest yields and qualities ofthe liquid products, consisting mainly of heavy soluble oligomers, which resulted in a high degree ofpolymerization
Bird\u27s eye view of star formation in the local Milky Way - How perspective changes with scale, time and viewing angle
Get PDFA crucial aspect in interpreting the scaling relations relevant for star formation—the Kennicutt-Schmidt relation and the Larson relations—is how those relations depend on size-scale. This is especially so when comparing relations derived from unresolved, extragalactic data to those derived from resolved, Galactic data. We present an experiment in which the Solar neighbourhood (distance < 2 kpc) is examined from the outside, with an aim to unveil the connection between the true, “resolved” properties of star-forming regions and their beam-averaged, “unresolved” properties. To do so, we examine the density, velocity and star formation statistics of the dust and molecular gas in the Solar neighbourhood and determine how it appears when viewed through apertures of various sizes. First, we employ sub-pc resolution dust column density maps and star formation rates of individual molecular clouds from the literature to study the scale dependencies of molecular cloud structure from sub-pc to kpc scales. Second, we study a complete three dimensional volume of the Milky Way between the scales of ∼ 2−800 pc, taking advantage of three dimensional dust maps and young stars from recent advances made using Gaia satellite data. This second dataset gives the possibility to study not only the scale dependency of star formation, but also the dependence on age and orientation angle in the Milky Way. In these two ways, we connect the average properties of the gas in the local Galactic environment to the resolved properties at cloud scales. Our results provide observational constraints for star formation models. They can also aid the interpretation of on-going and upcoming extragalactic observations, especially by shedding light on the sub-beam properties of the structures detected by them
Decarbonising the iron and steel industries: Production of carbon-negative direct reduced iron by using biosyngas
Get PDFBioenergy with carbon capture and storage (CCS) in iron and steel production offers significant potential for CO2 emission reduction and may even result in carbon-negative steel. With a strong ambition to reach net-zero emissions, some countries, such as Sweden, have recently proposed measures to incentivise bioenergy with CCS (BECCS), which opens a window of opportunities to enable the production of carbon-negative steel. One of the main potential applications of this route is to decarbonise the iron reduction processes that account for 85 % of the total CO2 emission in the iron and steel plants. In this study, gasification is proposed to convert biomass into biosyngas to reduce iron ore directly. Different cases of integrating the biomass gasifier, Direct Reduced Iron (DRI) shaft furnace, and CCS are evaluated through process simulation work. Based on the result of the work, the proposed biosyngas DRI route has comparable energy demand compared to other DRI routes, such as the well-established coal gasification and natural gas DRI route. The proposed process can also capture 0.65–1.13 t of CO2 per t DRI depending on the integration scenarios, which indicates a promising route to achieving carbon-negative steel production
Nanostructured Transition Metal Dichalcogenide Multilayers for Advanced Nanophotonics
Get PDFTransition metal dichalcogenides (TMDs) attract significant attention due to their exceptional optical, excitonic, mechanical, and electronic properties. Nanostructured multilayer TMDs were recently shown to be highly promising for nanophotonic applications, as motivated by their exceptionally high refractive indices and optical anisotropy. Here, this vision is extended to more sophisticated structures, such as periodic arrays of nanodisks and nanoholes with ultra sharp walls, as well as proof-of-concept all-TMD waveguides and resonators. Specific focus is given to various advanced nanofabrication strategies, including careful selection of resists for electron beam lithography and etching methods, especially for non-conductiven but relevant for nanophotonic applications substrates, such as SiO2. The specific materials studied here include semiconducting WS2, in-plane anisotropic ReS2, and metallic TaSe2, TaS2, and NbSe2. The resulting nanostructures can potentially impact several nanophotonic and optoelectronic areas, including high-index nanophotonics, plasmonics and on-chip optical circuits. The knowledge of TMD material-dependent nanofabrication parameters developed here will help broaden the scope of future applications of all-TMD\ua0nanophotonics
How do different micro-mobility vehicles affect longitudinal control? Results from a field experiment
Get PDFIntroduction:\ua0While micromobility vehicles offer new transport opportunities and may decrease fuel emissions, the extent to which these benefits outweigh the safety costs is still uncertain. For instance, e-scooterists have been reported to experience a tenfold crash risk compared to ordinary cyclists. Today, we still do not know whether the real safety problem is the vehicle, the human, or the infrastructure. In other words, the new vehicles may not necessarily be unsafe; the behavior of their riders, in combination with an infrastructure that was not designed to accommodate micromobility, may be the real issue.\ua0Method:\ua0In this paper, we compared e-scooters and Segways with bicycles in field trials to determine whether these new vehicles create different constraints for longitudinal control (e.g., in braking avoidance maneuvers).\ua0Results:\ua0The results show that acceleration and deceleration performance changes across vehicles; specifically, e-scooters and Segways that we tested cannot brake as efficiently as bicycles. Further, bicycles are experienced as more stable, maneuverable, and safe than Segways and e-scooters. We also derived kinematic models for acceleration and braking that can be used to predict rider trajectories in active safety systems.\ua0Practical Applications:\ua0The results from this study suggest that, while new micromobility solutions may not be intrinsically unsafe, they may require some behavior and/or infrastructure adaptations to improve their safety. We also discuss how policy making, safety system design, and traffic education may use our results to support the safe integration of micromobility into the transport system
Bridging the divide in energy policy research: Empirical evidence from global collaborative networks
Get PDFEnergy research seeking to influence policy in low- and middle-income countries (LMICs) is often funded by – and conceptualised by authors in – institutions from higher income countries (HICs). Research agendas and policy recommendations determined in HICs potentially yield the most influence on policymaking in LMICs. This risks leaving a multidimensional gap in how LMICs frame, evidence and enact policies. This paper is the first to provide quantitative evidence to geographical imbalances in energy policy research, and to shed light into the fact that research proposing energy policy coupled with development objectives to LMICs is dominated by HICs researchers. We find that the latter not only publish more articles proposing energy policy to LMICs, but also are more cited when doing so. We reach these findings by analysing the spatial dynamics of energy research on LMICs through a multi-method approach using bibliometric, network science and regression-based techniques. We established a framework using a sample of 6,636 papers from the Web of Science database, journal impact data from Scimago Journal Ranking and country economic data from the World Bank. Results show the existence of a cycle of imbalances across research practices. Most scientific articles recommending energy policy for LMICs have a primary author based in a HIC, funded by a HIC institution. The number of citations articles receive increases with the GDP of the country of primary author. Funders support authors based in countries of the same income band or higher. We recommend revising research practices and funding policies to place local actors and knowledge at the heart of energy policy research, enabling high-impact policymaking in LMICs