Moderate Drop Research Articles

Design of a partially narrowed flow channel with a sub-distribution zone for the water management of large-size proton exchange membrane fuel cells

With increased power density and flow field size of proton exchange membrane fuel cells (PEMFCs), water management becomes increasingly important for the exacerbated water accumulation in flow channels (FCs). Therefore, this study proposes a novel partially narrowed channel (PNC) with a sub-distribution zone as a promising alternative for FC design. In addition, a modified volume of fluid (VOF) method is developed using an equivalent contact angle to represent the effect of the rough surface of gas diffusion layer (GDL) on water drainage. Then, a comparison among different FCs and design of structural parameters are conducted. The results show that the highest water drainage efficiency of 9.88 % ms−1 is achieved with the liquid removed in a film state at the pressure drop of 5.01 kPa. Considering the sub-distribution zone, the location and interval of baffles significantly affect water drainage efficiency, while the shape has minimal effect. The highest water drainage efficiency is observed when the baffles are located between the channels with an interval of 2 and 3 mm at low and high airflow inlet velocities, respectively. The PNC with a sub-distribution zone removes liquid rapidly at a moderate pressure drop, thereby reducing pumping losses and risks of membrane degradation.

Investigating forced convection in porous media-filled cavities for designing supplementary passive cooling systems

This study aims to propose innovative passive cooling methods within the reservoir section of a closed-loop liquid cooling system. The techniques employed in this study include using a cold wall, a porous medium, varying inlet positions, and nozzles of different sizes and shapes. The effects of parameters associated with these techniques on outlet temperature reduction, pressure drop, and average Nusselt number (Nu¯) have been analyzed in detail. The reservoir section has been numerically modeled as a two-dimensional (2D) and a three-dimensional (3D) cavity. The numerical model implements mass, momentum, energy, and conservation equations for the Darcy model in the porous region. A fluid flow with Re=50 with a laminar generalized porous media modeling approach employing Brinkman’s and Forchheimer’s terms has been used. The optimized inlet position with respect to maximum cooling (55.60 K) and moderate pressure drop (2.30kPa) for the 2D cavity has been identified in this work for a given Darcy number and porosity. Results show that decreasing porosity improves convective heat transfer efficiency and increases pressure drop. Similarly, varying Darcy’s number affects heat transfer, with lower Da values resulting in reduced outlet temperature reduction and lower Nu¯, with higher pressure drop. A similar analysis was conducted for the 3D reservoir. The use of a converging nozzle can lead to an increase in cooling by 61.61% and 3.44% for the 2D and 3D reservoirs, respectively.

Novel Biobased Copolymers Based on Poly(butylene succinate) and Cutin: In Situ Synthesis and Structure Properties Investigations.

The present work describes the synthesis of poly(butylene succinate) (PBSu)-cutin copolymers by the two-stage melt polycondensation method, esterification and polycondensation. Cutin was added in four different concentrations, 2.5, 5, 10, and 20 wt%, in respect to succinic acid. The obtained copolymers were studied using a variety of techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), polarized light microscopy (PLM), as well as diffuse reflectance spectroscopy (DRS). A series of results, in agreement between different techniques, revealed the formation of PBSu-cutin interactions, confirming indirectly the successful in situ synthetic route of copolymers. DSC and XRD combined with PLM results provided indications that the crystallization temperature increases with the addition of small amounts of cutin and gradually decreases with increasing concentration. The crystallization process was easier and faster at 2.5%, 5%, and 10% concentrations, whereas at 20%, it was comparable to neat PBSu. The presence of cutin, in general, leads to the facilitated crystallizability of PBSu (direct effect), whereas a moderate drop in the glass transition temperature is recorded, the latter being an indirect effect of cutin via crystallization. The thermal stability improved in the copolymers compared to neat PBSu. Water contact angle measurements confirmed that the addition of cutin decreased the hydrophilicity. The local and segmental relaxation mapping is demonstrated for PBSu/cutin here for the first time. Enzymatic hydrolysis and soil degradation tests showed that, overall, cutin accelerated the decomposition of the polymers. The copolymers may be proven useful in several applications.

Enhancing thermal performance of heat exchanger by using different 4-lobed swirl tube arrangements

This study numerically and experimentally investigated the thermal performance of a 4-lobed swirl tube. A double-pipe heat exchanger was built using 3D-printed steel tubes with PD ratios ranging from 4, 6 to 8. In addition, a 3D-printed circular pipe was also manufactured to investigate the influence of the 3D-printing method. In the experimental results, the PD4 decaying swirl tube had the highest performance for all PD ratios. The effects of different pitch-to-diameter (PD) ratios and tube arrangements on the swirl pipe were also investigated during simulations. The results reveal that the tube with a smaller PD ratio and crossover arrangement has a larger thermal enhancement and pressure drop. However, in comparison, the decaying arrangement has a relatively higher overall performance since it has a lower pressure drop. The PD6 decaying tube arrangement is the highest, especially at higher Reynolds numbers. Moreover, by showing the streamline within the swirl tube, small-scale vortices are found within the swirl tube, especially in the crossover arrangement. These vortices are formed due to the swirl motion and can enhance mixing and the heat transfer rate. Based on these simulation results, a regular-spaced swirl tube arrangement is proposed and its thermal performance is evaluated. In the experimental results, the PD4 decaying swirl tube gave the highest overall performance from 1.12 to 1.09 across all configurations. In the numerical results, the regularly-spaced swirl tube can further improve the overall performance with moderate pressure drop. Type 2 PD4 has the highest performance value at 1.06.

Trait‐specific sensitive developmental windows: Wing growth best integrates weather conditions encountered throughout the development of nestling Alpine swifts

AbstractThe size and growth patterns of nestling birds are key determinants of their survival up to fledging and long‐term fitness. However, because traits such as feathers, skeleton and body mass can follow different developmental trajectories, our understanding of the impact of adverse weather on development requires insights into trait‐specific sensitive developmental windows. We analysed data from nestling Alpine swifts in Switzerland measured throughout growth up to the age of 50 days (i.e. fledging between 50 and 70 days), for wing length and body mass (2693 nestlings in 25 years) and sternum length (2447 nestlings in 22 years). We show that the sensitive developmental windows for wing and sternum length corresponded to the periods of trait‐specific peak growth, which span almost the whole developmental period for wings and the first half for the sternum. Adverse weather conditions during these periods slowed down growth and reduced size. Although nestling body mass at 50 days showed the greatest inter‐individual variation, this was explained by weather in the two days before measurement rather than during peak growth. Interestingly, the relationship between temperature and body mass was not linear, and the initial sharp increase in body mass associated with the increase in temperature was followed by a moderate drop on hot days, likely linked to heat stress. Nestlings experiencing adverse weather conditions during wing growth had lower survival rates up to fledging and fledged at later ages, presumably to compensate for slower wing growth. Overall, our results suggest that measures of feather growth and, to some extent, skeletal growth best capture the consequences of adverse weather conditions throughout the whole development of offspring, while body mass better reflects the short, instantaneous effects of weather conditions on their body reserves (i.e. energy depletion vs. storage in unfavourable vs. favourable conditions).

Dynamic Model Validation and Simulation of Acetone-Toluene and Benzene-Toluene Systems for Industrial Volatile Organic Compound (VOC) Abatement.

Environmental impact mitigation is one of the grand challenges for industries globally. Volatile organic compounds (VOCs) are solvents whose emissions are potentially toxic to human health and ecosystems yet indispensable for the manufacturing of life-saving medicine. Adsorption with activated carbon columns is an established countermeasure for end-of-pipe emission control, whose efficiency, however, is impeded by irregular bed saturation due to the complex nature of its inputs. This work presents the application of a validated nonisothermal adsorption model to examine multicomponent trace mixtures of acetone-toluene and benzene-toluene on activated carbon. Our results indicate preferential adsorption of toluene over both acetone and benzene for all concentrations examined, which is in agreement with experimental data. Moreover, moderate temperature variations and pressure drops are revealed. Finally, Glueckauf's hodograph theory is employed for maximum outlet concentration prediction and compared with simulation results and experimental data, thus providing valuable insights into nonisothermal VOC abatement, which paves the way for industrial operation optimization.

Numerical Study of Rarefied Gas Flow in Diverging Channels of Finite Length at Various Pressure Ratios

In the present work, the gas flows through diverging channels driven by small, moderate, and large pressure drops are studied, considering a wide range of the gas rarefaction from free molecular limit through transition flow regime up to early slip regime. The analysis is performed using the Shakhov kinetic model, and applying the deterministic DVM method. The complete 4D flow problem is considered by including the upstream and downstream reservoirs. A strong effect of the channel geometry on the flow pattern is shown, with the distributions of the macroscopic quantities differing qualitatively and quantitatively from the straight channel flows. The mass flow rate data set from the complete solution is compared with the corresponding set obtained from the approximate kinetic methodology, which is based on the fully developed mass flow rate data available in the literature. In addition, the use of the end-effect approach significantly improves the applicability range of the approximate kinetic methodology. The influence of the wall temperature on the flow characteristics is also studied and is found to be strong in less-rarefied cases, with the mass flow rate in these cases being a decreasing function of the temperature wall. Overall, the present analysis is expected to be useful in the development and optimization of technological devices in vacuum and aerospace technologies.

The influence of submillimeter morphological variations on the wettability of WEDM-fabricated dual-scale roughness aluminum alloy 6082 surfaces

Deriving inspiration from natural hierarchical superhydrophobic surfaces, multi-scale structures were manufactured on AA6082 surfaces via wire electrical discharge machining (WEDM), featuring microscale texture due to spark erosion, superimposed upon a wide-range simple and more complicated geometries of submillimeter profiles. The effect that the higher-order scale morphologies had on wettability was investigated. The dual-scale morphology elevated the hydrophobicity of the surfaces compared to single-scale or unmodified surfaces, reaching superhydrophobicity (151°) in the case of a certain triangular profile. Rectangular and triangular profiles facilitated the higher contact angles, while re-entrant geometries were able to totally prevent cavity wetting. A correlation of static contact angle with roughness parameters of the larger scale such as Ra, Rz, Rp, Rsk, and Rku for certain geometry configurations was identified. Peak hydrophobicity resulted at Ra = 70 μm, Rz = 240 μm, and Rp = 160 μm concerning simple geometries. Negative Rsk and Rku > 1.5 affected negatively contact angle of samples. All investigated tested types were found to reach higher hydrophobicity at moderate drop volumes (5 μl). The fabricated samples were anisotropic in at least two directions, showing decreased hydrophobicity in the front, parallel to the groove direction. When tested in multi-directional dynamic tilting up to 90°, the more complicated geometries were able to retain resistance to spreading. All samples demonstrated superliquiphilicity with lower surface tension liquids, making them strong candidate in applications such as oil/water separation. Finally, all samples tested sustained their hydrophobic character subsequent to a 3-month atmospheric exposure period.

Development of Cellulose Air Filters for Capturing Fine and Ultrafine Particles through the Valorization of Banana Cultivation Biomass Waste

Outdoor and indoor atmospheric pollution is one of the major problems that humanity continues to face. As a mitigation pathway, numerous technologies have been developed for air purification, including the use of fibrous filters. In this study, the particle capture efficiencies and pressure drops of air filters manufactured with cellulose pulp extracted from banana pseudostems were studied across three particle size ranges (PM10, PM2.5, and PM1). Two pretreatments were applied, alkaline with soda-antraquinone (alkali-treated pulp) and a subsequent bleaching process (bleached pulp), and four manufacturing processes were tested: crushing, freeze-drying, vacuum filtration, and pressing. In addition, a study varying filter grammage (70, 100, and 160 g·m−2) and pressing pressures (2, 4, 6, and 8 t) was also performed. After conducting these particle tests, the filter manufactured with bleached pulp, having a grammage of 160 g·m−2 and pressed at 4 t, was deemed the optimal individual solution. It demonstrated high particle retention efficiencies across all particle size ranges (with values exceeding 80%), a moderate pressure drop below 1000 Pa, and high thermal stability (degradation above 220 °C). However, combining freeze-drying and two-ton pressing processes yielded improved results (83% for the smallest particles and 89% for others) with approximately half the pressure drop. Based on these results, this study stands as a noteworthy contribution to waste valorization and the advancement of environmentally friendly materials for particle air filters. This is achieved through the adoption of simple and cost-effective technology, coupled with the utilization of 100% natural agricultural waste as the primary manufacturing material.

Fabrication of ε-Poly-L-lysine (ε-PL) modified electrospun antibacterial nanofibrous membranes for PM1.0 filtration

Segregating airborne particulate matters (PMs, especially PM1.0) with high transmissibility of bacterial and viral pathogens is crucial for ensuring outdoor breathing safety. Electrospun nanofiber membranes (ENMs) have shown great promise for this purpose. However, the application of traditional ENMs is usually plagued by bacterial growth causing severe public health concern. Although some research has been done to overcome this challenge by doping antibacterial materials, the potential negative effects of these materials on the human body cannot be ignored. In this study, the ε-Poly-L-lysine (ε-PL), a green broad-spectrum antibacterial reagent, was grafted onto the surface of polydopamine (PDA) coated polyacrylonitrile (PAN) ENM via addition of Schiff base and Michael reaction. Experimental results indicated that the introduction of the ε-PL is key to the antibacterial performance of the membranes, and the antibacterial efficacy of E. coli and B. subtilis can reach to 99.86 % and 99.99 % respectively. Even after 7 days, the antibacterial efficiency of membrane remained at a high level. Additionally, the uniform structure of membranes endowed it with a high filtration efficiency of 80.9 % for PM1.0 particles with a moderate transmembrane pressure drop (TMP) of 250 Pa and the corresponding quality factor is approximately 0.0066 Pa−1. This study has far-reaching implications for the design of green antibacterial nanofibrous membranes to realize the segregation of harmful PMs.

Altered DTI scalars in the hippocampus are associated with morphological and structural changes after traumatic brain injury.

Blunt and diffuse injury is a highly prevalent form of traumatic brain injury (TBI) which can result in microstructural alterations in the brain. The blunt impact on the brain can affect the immediate contact region but can also affect the vulnerable regions like hippocampus, leading to functional impairment and long-lasting cognitive deficits. The hippocampus of the moderate weight drop injured male rats was longitudinally assessed for microstructural changes using in vivo MR imaging from 4h to Day 30 post-injury (PI). The DTI analysis found a prominent decline in the apparent diffusion coefficient (ADC), radial diffusivity (RD), and axial diffusivity (AD) values after injury. The perturbed DTI scalars accompanied histological changes in the hippocampus, wherein both the microglia and astrocytes showed changes in the morphometric parameters at all timepoints. Along with this, the hippocampus showed presence of Aβ positive fibrils and neurite plaques after injury. Therefore, this study concludes that TBI can lead to a complex morphological, cellular, and structural alteration in the hippocampus which can be diagnosed using in vivo MR imaging techniques to prevent long-term functional deficits.

Enhancement of oxidative stability of polyunsaturated fatty acid‐rich fish oil: microencapsulation using chitosan‐whey protein complex and betalain

SummaryPolyunsaturated fatty acids (PUFAs), which are abundant in fish oil, easily oxidise. Therefore, stabilisation is necessary, preferably through encapsulation and the addition of antioxidants. This research looked on multiple emulsification for PUFA‐rich fish oil by utilising a wall material (whey protein and chitosan) and an antioxidant (betalain) combination. Spray‐dried, microparticles filled with PUFA were successfully created (80% yield) and characterised. It was determined that the emulsion droplet size was 0.917 μm. Good oxidative stability was observed after 4 weeks of storage, as evidenced by a moderate (4%) drop in EPA and DHA content and a low peroxide value (PV) of 4.8 ± 0.23 meq/kg oil in microparticles. Microencapsulation of PUFA‐rich fish oil was successfully accomplished using multiple emulsion technology, as evidenced by encapsulation efficiency values of 87.73 ± 0.21% and loading efficiency values of 67 ± 0.11%. These results suggest that structurally stabilised healthful lipids could be added to foods using these innovative emulsions, which provide greater stability and versatility for a wide variety of uses.

Numerical Performance Investigation of a Side‐outlet Cyclone for Particulate Matter and Polymer Powder Separation

AbstractThe side‐outlet cyclone, featuring a novel geometric design with a lateral gas outlet, proves advantageous in space‐constrained environments compared to traditional cyclones with top gas outlets. Herein, a cyclone separator with a side‐outlet configuration was numerically investigated using the renormalization group k‐ε model and pressure drop and separation efficiency as the performance parameters. Simulation results revealed that the side‐outlet cyclone operates at a low to moderate pressure drop of 80.8412 Pa, with a removal efficiency of 45.48 %. The operating pressure drop was found to be only one‐third of the computed pressure drop from mathematical modeling, with a removal efficiency 15 % lower than the experimental value. With varying cyclone design modifications, suitable experimental procedures and measuring approaches are desirable to further accurately corroborate these results.

Cardiovascular and Vector-Cardiographic Effects of Articaine Anesthesia with Epinephrine.

The aim was to investigate the vector-cardiographic effects in patients submitted to dental extraction under local anesthesia. Twenty-one patients aged 36.6 ± 12.4 years with a clinical and radiographic indication of mandibular or maxillary tooth extraction were enrolled. The intervention was a local or mandibular nerve block anesthesia with 4% articaine hydrochloride containing epinephrine (1 : 100,000; 40 mg/ml + 10 μg/ml). Blood pressure (BP), heart rate (HR), pulse wave transit time, and vector-cardiography data were recorded throughout 3 min before and 5 min after injection. QRS- and T-wave area under the curve (QRS AUC/T AUC) were calculated from the X/Y/Z QRS-vector or T-vector. T-wave amplitude (T AM), T AUC values, and diastolic BP decreased, and HR significantly increased 4 min after injection. A transient moderate HR drop and a corresponding small increase in T AM and T AUC immediately after the injection procedure may be explained by a decreased sympathetic tone due to psychological relief. In dental anesthesia, the systemic epinephrine effects are represented by a decrease in T AUC. These effects are most pronounced in the X- and Y-leads. The 3D determination of vector planes or amplitudes is a simple method to register the sympathetic tone in local anesthesia independently of possible effects on T-wave characteristics in single leads. In conclusion, T-wave determination may help to detect even small increases in systemic adrenaline concentration in case of accidental intravascular injection. At the same time, full rhythm and spatial ischemia control is provided.

Experimental and numerical study on thermofluidic characteristics of microchannel heat sinks with various micro pin-fin arrays arrangement patterns

Targeting at improving the comprehensive performance of microchannel heat sink, microchannel heat sinks integrated with various arrangements of micro pin-fins arrays are proposed in this paper. The thermofluidic characteristics and heat transfer enhancement mechanism of different pin-fins arrangement patterns is investigated by experimental test and numerical simulations. It is found that the partially uniform/gradient stagger pin-fins arrangement patterns present largest pressure drop with moderate heat dissipation performance, while the patterns with overall pin-fins distribution demonstrate superior heat transfer performance than all partial pin-fins distribution modes. Thus, overall gradient stagger pin-fins arrangement with moderate pressure drop yields optimal heat transfer capacity, achieving 4.8∼6.1 times enhancement than smooth channel. Furthermore, the partially uniform/gradient stagger pin-fins arrangement patterns indicate best temperature uniformity and thermal resistance with 26.2 K and 47.6% reduction than smooth channel at 80 ml/min, 100 W/cm2, respectively. The temperature trend in the longitudinal direction shows peaks and troughs for arrangements with partial pin fins distribution, while patterns of gradient pin fins distribution exhibit wavy curves of temperature rise. Additionally, the performance evaluation plot is adopted to describe the comprehensive performance of heat sinks with different pin fins patterns. It is observed that the overall gradient stagger pin-fins arrangement shows optimal comprehensive performance among all patterns, achieving heat transfer enhancement ratio greater than 4 in contrast with smooth channel. Finally, the correlations of Nusselt number and apparent friction factor for patterns are established. This study provides feasible insights on the performance improvement of microscale liquid cooling technologies for thermal management of electronic devices.

Changes in oxygen delivery during experimental models of cerebral malaria

Cerebral malaria (CM) is a severe manifestation of malaria that commonly occurs in children and is hallmarked by neurologic symptoms and significant Plasmodium falciparum parasitemia. It is currently hypothesized that cerebral hypoperfusion from impaired microvascular oxygen transport secondary to parasitic occlusion of the microvasculature is responsible for cerebral ischemia and thus disease severity. Animal models to study CM, are known as experimental cerebral malaria (ECM), and include the C57BL/6J infected with Plasmodium berghei ANKA (PbA), which is ECM-susceptible, and BALB/c infected with PbA, which is ECM-resistant. Here we sought to investigate whether changes in oxygen (O2) delivery, O2 flux, and O2 utilization are altered in both these models of ECM using phosphorescence quenching microscopy (PQM) and direct measurement of microvascular hemodynamics using the cranial window preparation. Animal groups used for investigation consisted of ECM-susceptible C57BL/6 (Infected, n = 14) and ECM-resistant BALB/c (Infected, n = 9) mice. Uninfected C57BL/6 (n = 6) and BALB/c (n = 6) mice were included as uninfected controls. Control animals were manipulated in the exact same way as the infected mice (except for the infection itself). C57BL/6 ECM animals at day 6 of infection were divided into two cohorts: Early-stage ECM, presenting mild to moderate drops in body temperature (>34 < 36 °C) and Late-stage ECM, showing marked drops in body temperature (<33 °C). Data taken from new experiments conducted with these animal models were analyzed using a general linear mixed model. We constructed three general linear mixed models, one for total O2 content, another for total O2 delivery, and the third for total O2 content as a function of convective flow. We found that in both the ECM-susceptible C57BL/6J model and ECM-resistant BALB/c model of CM, convective and diffusive O2 flux along with pial hemodynamics are impaired. We further show that concomitant changes in p50 (oxygen partial pressure for 50% hemoglobin saturation), only 5 mmHg in the case of late-stage CM C57BL/6J mice, and O2 diffusion result in insufficient O2 transport by the pial microcirculation, and that both these changes are required for late-stage disease. In summary, we found impaired O2 transport and O2 affinity in late-stage ECM, but only the former in either early-stage ECM and ECM-resistant strains.

Doppler Sodar Measured Winds and Sea Breeze Intrusions over Gadanki (13.5° N, 79.2° E), India

Doppler sodar measurements were made at the tropical Indian station, i.e., Gadanki (13.5° N, 79. 2° E). According to wind climatologies, the wind pattern changes from month to month. In July and August, the predominant wind direction during the monsoon season was the southwest. In September, it was the northwest and south. While the winds in November came from the northeast, they came from the northwest and southwest in October. The winds in December were out of the southeast. The diurnal cycle of winds at 60-m above the ground was visible, with disturbed wind directions in September and October. This may be connected to the Indian subcontinent’s southeastern monsoon recession. To better understand the monsoon circulation on a monthly basis, the present work is innovative in that it uses high-resolution winds measured using the Doppler sodar at the atmospheric boundary layer. The convergence of a sea breeze and the background wind might result in a sudden change in wind direction, and forecasting such a chaotic atmospheric event is crucial in the aviation sector. As a result, the wind shear that is produced may pose a serious threat to airplanes that are landing. In the current study, we present a few cases of sea breeze intrusions. The physics underlying these intrusions may help modelers better understand these chaotic wind structures and use them as inputs in their models. Based on surface-based atmospheric characteristics, there have been two reports of deep sea breeze intrusions that we report in this research. The sea breeze days were marked by substantial (moderate) drops in temperature (dewpoint temperatures) and increased wind speed and relative humidity. The India Meteorological Department (IMD) rainfall data showed a rise in precipitation over this location on 23 July (4.8 mm) and 24 July (9.5 mm) when sea breeze intrusions over Gadanki were noticed. Sea breeze intrusions could have brought precipitation (intrusion-laden precipitation) to this area due to conducive meteorological conditions. A simple schematic model is proposed through a diagrammatic illustration that explains how a sea breeze triggers precipitation over adjacent locations to the seacoast. The skew-T log-P diagrams have been drawn using the balloon-borne radiosonde measured atmospheric data over Chennai (a nearby location to Gadanki) to examine the thermodynamic parameters to gain insights into the underlying mechanisms and meteorological conditions during sea breeze intrusion events. It is found that the convective available potential energy (CAPE), which is presented as a thermos diagram, was associated with large values on 23 July and 24 July (898 J/kg and 1250 J/kg), which could have triggered thunderstorms over Chennai.

Numerical Assessment of Flow Energy Harvesting Potential in a Micro-Channel

A micro-energy harvesting device proposed in the literature was numerically studied. It consists of two bluff bodies in a micro-channel and a flexible diaphragm at its upper wall. Vortex shedding behind bodies induces pressure fluctuation causing vibration of the diaphragm that converts mechanical energy to electrical by means of a piezoelectric membrane. Research on enhancing vortex shedding was justified due to the low power output of the device. The amplitude and frequency of the unsteady pressure fluctuation on the diaphragm were numerically predicted. The vortex shedding severity was mainly assessed in terms of pressure amplitude. The CFD model set-up was described in detail, and appropriate metrics to assess the energy harvesting potential were defined. Several 2D cases were simulated to study the effect of the inlet Reynolds number and channel blockage ratio on the prospective performance of the device. Furthermore, the critical blockage ratio leading to the vortex shedding suppression was sought. A higher inlet velocity for a constant blockage ratio was found to enhance vortex shedding and the pressure drop. Great blockage ratio values but lower than the critical ones seemed to provide great pressure amplitudes at the expense of a moderate pressure drop. There is evidence that the field is fruitful for further research and relevant directions were provided.

Effects of extreme heat on milk quantity and quality

CONTEXTHeat exposure, particularly when co-occurring with extreme humidity levels, is amongst the most pronounced and challenging extreme weather conditions in European dairy production. Since these conditions are expected to increase in magnitude and frequency due to climate change, it is crucial to better understand the actual impact under managed production within the European dairy farm population. OBJECTIVEIn this paper, we estimate the impact of heat stress, i.e. hot and humid weather conditions on milk quantity and quality in Flanders, a high intensity dairy production region in Belgium. The novelty of our approach is twofold. First, we provide insights in the non-linear response of dairy production (quantity and quality) to extreme heat using farm-level production data. Second, using data from the entire population of farmers in Flanders, and covering 6 years (N = 178.843), our results provide a maximum of representativeness and allows to infer on economic relevance of the effects. METHODSWe use monthly milk deliveries within the grazing season for the period 2009 to 2014, which we match with temperature and humidity conditions at the barn-level. Using fixed effects regression, we particularly focus on heat shocks, i.e. the deviations from the average climate at the barn location, on production shocks, i.e. deviations from the average production of the barn. We use non-linear restricted cubic splines regression to estimate the response of milk quality and quantity to hourly temperature-humidity (THI) exposure. RESULTS AND CONCLUSIONWe find reductions of milk quantity and protein contents under hot and humid conditions, while milk fat content appears unaffected. These results are in contrast to earlier findings of heat exposure on dairy production in two ways. First, we find the critical temperature-humidity threshold above which production is affected to be substantially higher than in earlier/experimental studies. Second, not all quality components are affected by these conditions. We conclude that under managed conditions, farmers seem to be partly able to adapt their production to moderate heat exposure. SIGNIFICANCEOur results deliver important implications for policy makers and agricultural practitioners. While we find that farmers seem to be able to cope with moderate heat conditions, milk quality and quantity drop under extreme heat conditions. These impacts are economically relevant.

The Cuprizone Mouse Model: A Comparative Study of Cuprizone Formulations from Different Manufacturers.

The Cuprizone mouse model is widely used in studies on de- and remyelination. In the hands of different experimenters, the Cuprizone concentrations that lead to comparable levels of demyelination differ considerably. The reasons for this variability are unknown. In this study, we tested whether different Cuprizone formulations from different vendors and manufacturers influenced Cuprizone-induced histopathological hallmarks. We intoxicated male C57BL/6 mice with six Cuprizone powders that differed in their manufacturer, vendor, and purity. After five weeks, we analyzed the body weight changes over the course of the experiment, as well as the demyelination, astrogliosis, microgliosis and axonal damage by histological LFB-PAS staining and immunohistochemical labelling of PLP, IBA1, GFAP and APP. All Cuprizone formulations induced demyelination, astrogliosis, microgliosis, axonal damage and a moderate drop in body weight at the beginning of the intoxication period. In a cumulative evaluation of all analyses, two Cuprizone formulations performed weaker than the other formulations. In conclusion, all tested formulations did work, but the choice of Cuprizone formulation may have been responsible for the considerable variability in the experimental outcomes.