Lean premixed opposed jet flames in fractal grid generated multiscale turbulence

The opposed jet configuration presents an attractive canonical geometry for the evaluation of burning properties of turbulent flames with past studies typically limited to low Reynolds numbers. Fractal grid generated turbulence was used to remove the low turbulence level limitations associated with conventional perforated plate generators with the turbulent Reynolds number range moved from 50–120 to 130–318. Optimal grid configurations were determined with particular emphasis on reducing the impact of the flow upstream of the turbulence generators in order to facilitate simpler boundary conditions for computational studies. The resulting flow structures were analysed using proper orthogonal decomposition and conditional proper orthogonal decomposition. Velocity and reaction progress variable statistics, including conditional velocities and scalar fluxes, are reported for fuel lean methane, ethylene and propane flames approaching extinction. The instrumentation comprised particle image velocimetry with the flows to both nozzles seeded with 1 μm silicon oil droplets or 3 μm Al₂O₃ particles. Probability density functions were determined for the instantaneous location of the stagnation point to eliminate the possibility of low frequency bulk motion distorting velocity statistics. Probability density functions of flame curvature were determined using a multi-step flame front detection algorithm with estimates of the turbulent burning velocity provided along with a discussion of alternative determination methods. The data sets show that fractal grids generate multi-scale broadband turbulence and present an opportunity for a systematic evaluation of calculation methods for premixed turbulent flames that undergo a transition from non-gradient to gradient turbulent transport while approaching extinction.     

Yb-doped WO3 photocatalysts for water oxidation with visible light

Yb-doped WO₃ photocatalysts were prepared by co-sputtering WO₃ and Yb, followed by annealing in air for water oxidation with visible light. All the obtained photocatalysts were monoclinic with sputtering power of Yb up to 10 W and displayed no optical absorption red shift. In photoelectrochemical (PEC) studies, the photocurrent densities were improved with up to 0.34 at.% Yb in WO_3, with the highest photocurrent of 1.3 mA/cm² (1.2 V vs. Ag/AgCl) achieved with <0.1 at.% Yb. Electrochemical impedance spectroscopy (EIS) measurements showed that optimized Yb doping reduced charge transfer resistance and increased donor density of WO₃ photocatalyst. The improvement in photocurrent density was attributed to enhanced conductive carrier path, increased oxygen vacancies and 4f¹³ orbital configuration due to Yb³⁺ substitution of W⁶⁺.     

W/O/W emulsions with high internal droplet volume fraction

We prepared water-in-oil-in-water (W/O/W) double emulsions with high internal aqueous droplet fraction using food-based ingredients. These compartmentalised materials were comprised of oil globules dispersed in an external aqueous phase, with the globules themselves containing densely packed inner aqueous droplets. We were able to obtain double emulsions with large globule fractions (up to 45 vol.%) using only 5 vol.% oil (relative to the overall composition). In the final state, the inner droplet fraction within the globules could exceed 90 vol.%. The method was based on two successive emulsification steps, followed by osmotic swelling (transport of water from the external phase to the inner droplets through the oil phase). During the final step, the swelling was controlled by the osmotic pressure mismatch between the external and internal aqueous phases using solutes dissolved at different concentrations. The osmotic swelling model of Mezzenga et al. (Langmuir, 2004, 20, 3574-3582) was re-adapted in the limit of small Laplace pressures to predict the final composition resulting from osmotic equilibration. The internal droplet fraction was lower than that predicted by the model as a consequence of coalescence phenomena occurring during the swelling process. The proposed approach constitutes a valuable guide within the prospect of formulating emulsions with enhanced encapsulation capacity and reduced fat content.     

Microscopic and spectroscopic study of self-ordering in poly(3-hexylthiophene)/carbon nanotubes nanocomposites

Poly(3-hexylthiophene)-single-walled carbon nanotubes (SWNTs) composites were studied using UV-visible absorbance and Raman spectroscopy, scanning tunneling microscopy (STM) and transmission electron microscopy (TEM). Monolayers of regioregular poly(3-hexyl thiophene) (rrP3HT) adsorbed on SWNTs have been imaged using scanning tunneling microscopy (STM) to obtain measurements of the chiral angles at which the thiophene polymer chains wrap around individual carbon nanotubes (41-48 degrees with respect to nanotube axis) and polymer interchain spacings (1.68 angstroms). The rrP3HT interchain distance is greater for rrP3HT monolayers adsorbed onto the curved surfaces of SWNTs than on the flat surfaces of highly ordered pyrolytic graphite samples (1.4 angstroms). UV-vis spectroscopic data provided strong evidence for increased interchain interactions in composites of rrP3HT and SWNTs compared to the pure polymer. The STM local-probe studies of the native polymer and the composites further confirmed that the rrP3HT interacts with carbon nanotubes to produce a highly ordered material at the molecular level.     

Formation of Sn–Bi solder alloys by sequential electrodeposition and reflow

Eutectic Sn–Bi alloy is gaining considerable attention in the electronic packaging industry because of its favorable properties such as low melting temperature, good wettability, and good mechanical properties. Miniaturization of electronic devices requires small solder bumps, a few tens of micrometers in diameter. Electrodeposition is a reliable technique for the deposition of small volume of solder. This work focuses on the formation of eutectic Sn–Bi solder by reflowing a metal stack containing sequentially electrodeposited Sn and Bi layers. The effects of layering sequence on the composition and microstructure of the resulting alloy is investigated. Irrespective of the layering sequence, a homogeneous microstructure is achieved after reflow. The microstructure of the reflowed samples is the same as that of a metallurgically processed Sn–Bi alloy. Near-eutectic alloy with the composition Sn–54.6 wt% Bi is obtained by the sequential electrodeposition method.     

The Relationship between COVID-19 and Hypothalamic–Pituitary–Adrenal Axis: A Large Spectrum from Glucocorticoid Insufficiency to Excess—The CAPISCO International Expert Panel

Coronavirus disease 2019 (COVID-19) is a highly heterogeneous disease regarding severity, vulnerability to infection due to comorbidities, and treatment approaches. The hypothalamic–pituitary–adrenal (HPA) axis has been identified as one of the most critical endocrine targets of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that might significantly impact outcomes after infection. Herein we review the rationale for glucocorticoid use in the setting of COVID-19 and emphasize the need to have a low index of suspicion for glucocorticoid-induced adrenal insufficiency, adjusting for the glucocorticoid formulation used, dose, treatment duration, and underlying health problems. We also address several additional mechanisms that may cause HPA axis dysfunction, including critical illness-related corticosteroid insufficiency, the direct cytopathic impacts of SARS-CoV-2 infection on the adrenals, pituitary, and hypothalamus, immune-mediated inflammations, small vessel vasculitis, microthrombotic events, the resistance of cortisol receptors, and impaired post-receptor signaling, as well as the dissociation of ACTH and cortisol regulation. We also discuss the increased risk of infection and more severe illness in COVID-19 patients with pre-existing disorders of the HPA axis, from insufficiency to excess. These insights into the complex regulation of the HPA axis reveal how well the body performs in its adaptive survival mechanism during a severe infection, such as SARS-CoV-2, and how many parameters might disbalance the outcomes of this adaptation.     

Routing and scheduling of wardens for public car park inspection

This paper presents a case study on the inspection operations of public car parks which employ a “coupon parking” system with checking by wardens. The problem is to determine an optimal staffing level for the wardens as well as an optimal schedule for their deployment. A framework is laid out in the paper for modeling the car park inspection policy, and some heuristic procedures are developed for the determination of number of wardens required in a zone. The proposed model has been tested against some field data, leading to results that provide a more rational and systematic basis for the scheduling of inspection operations.     

The Importance of mTORC1-Autophagy Axis for Skeletal Muscle Diseases

The mechanistic target of rapamycin (mTOR) complex 1, mTORC1, integrates nutrient and growth factor signals with cellular responses and plays critical roles in regulating cell growth, proliferation, and lifespan. mTORC1 signaling has been reported as a central regulator of autophagy by modulating almost all aspects of the autophagic process, including initiation, expansion, and termination. An increasing number of studies suggest that mTORC1 and autophagy are critical for the physiological function of skeletal muscle and are involved in diverse muscle diseases. Here, we review recent insights into the essential roles of mTORC1 and autophagy in skeletal muscles and their implications in human muscle diseases. Multiple inhibitors targeting mTORC1 or autophagy have already been clinically approved, while others are under development. These chemical modulators that target the mTORC1/autophagy pathways represent promising potentials to cure muscle diseases.     

Application of central composite design for optimization of bio-oil production using peat moss

Most nations have concentrated on reducing greenhouse gas emissions since global warming is such a serious problem. Due to land use changes, the harvesting of peat for use as fuel in homes, and the gardening industry, peat moss from peat bogs or peat fields may cause smoldering fires and release quantities of carbon dioxide. Bio-fuel is one of the alternative renewable sources created from organic materials. Pyrolysis, a thermochemical process that converts organic materials into substitutes for fossil fuels and used to create biofuel because it is readily available, straightforward, and inexpensive to implement. The feedstock utilized in this experiment was peat moss. Proximate and ultimate analyses were performed using thermogravimetric analysis and elemental analyzer to determine thermal breakdown and elemental characteristics. Pyrolysis was carried out in this work using a prototype lab scale fixed-bed pyrolysis. Based on prior study, the parameters used are pyrolysis temperature, nitrogen flow rate and reaction time to create the central composite design model. According to the analysis of variance results, pyrolysis temperature and flow rate were significant, however reaction time was not. The effect of flow rate and reaction time on response was explored. The actual bio-oil yield achieved utilizing the optimal parameters was 10.02 %. The presence of chemical compounds in bio-oil was measured.     

Thermal Performance Simulation of Eco-Friendly Lightweight Foamed Concrete Incorporating Palm Oil Fuel ash and Eggshell Powder Using ABAQUS

Silicon - The need for thermal insulating building material due to increase in Urban Heat Island effect and the carbon footprint associated with concrete due to its binder, cement, has caused...