Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or ...expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units-which we call metamaterial bricks-each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field. We apply this methodology to show experimental examples of acoustic focusing, steering and, after stacking single meta-surfaces into layers, the more complex field of an acoustic tractor beam. We demonstrate experimentally single-sided air-borne acoustic levitation using meta-layers at various bit-rates: from a 4-bit uniform to 3-bit non-uniform quantization in phase. This powerful methodology dramatically simplifies the design of acoustic devices and provides a key-step towards realizing spatial sound modulators.
Protein misfolding and aggregation is observed in many amyloidogenic diseases affecting either the central nervous system or a variety of peripheral tissues. Structural and dynamic characterization ...of all species along the pathways from monomers to fibrils is challenging by experimental and computational means because they involve intrinsically disordered proteins in most diseases. Yet understanding how amyloid species become toxic is the challenge in developing a treatment for these diseases. Here we review what computer, in vitro, in vivo, and pharmacological experiments tell us about the accumulation and deposition of the oligomers of the (Aβ, tau), α-synuclein, IAPP, and superoxide dismutase 1 proteins, which have been the mainstream concept underlying Alzheimer’s disease (AD), Parkinson’s disease (PD), type II diabetes (T2D), and amyotrophic lateral sclerosis (ALS) research, respectively, for many years.
This investigation aimed to enhance the functionality and minimize the harmful emissions of a diesel engine operating under various fuel blends, engine loads, and speeds using both standard ...techniques and an experimentally designed table (L16 orthogonal array) made with Taguchi's strategy of experimental design. The investigation's design had three governing parameters: fuel type, engine load, and engine speed. Each of these had four levels. The L16 orthogonal array (OA) was used to measure the operational characteristics, such as brake thermal efficiency (BTE) and brake-specific energy consumption (BSEC), as well as the pollution attributes such as brake-specific hydrocarbon (BSHC), brake-specific carbon monoxide (BSCO), and brake-specific nitrogen oxide (BSNO). Signal-to-noise (S/N) ratio and grey analysis were used to find the engine's best operating state so that it could get the most out of its performance while putting out the least amount of pollution. The study showed that engine load was the most influencing parameter for both BTE and BSEC, with contribution ratios of 84.02% and 86.79%, respectively. At 25% engine load, 1000 rpm, and using 20% orange peel biodiesel blended 100 ppm CNT impregnated diesel (OPB20CNT100) fuel (A1–B1–C4), the emissions of BSCO, BSNO, and BSHC were at their lowest levels. Engine load has the most significant impact on emissions. The engine's BSEC reduces by 4.35%, and BSNO emissions increased by 1.24%. BTE, BSCO, and BSHC emissions dropped by 3.1%, 16.96%, and 40.06%, respectively, under the best operating conditions compared to diesel fuel. The investigation demonstrates that the application of Taguchi–Grey optimization technique improves both the operational performance and pollution characteristics of diesel engines. The results showed that biodiesel made from orange peel and impregnated with CNT may be utilized as a sustainable alternative to diesel fuel.
Eph receptors are the largest family of receptor tyrosine kinases and by interactions with ephrin ligands mediate a myriad of processes from embryonic development to adult tissue homeostasis. The ...interaction of Eph receptors, especially at their transmembrane (TM) domains is key to understanding their mechanism of signal transduction across cellular membranes. We review the structural and functional aspects of EphA1/A2 association and the techniques used to investigate their TM domains: NMR, molecular modelling/dynamics simulations and fluorescence. We also introduce transmembrane peptides, which can be used to alter Eph receptor signaling and we provide a perspective for future studies.
All for one and one for all: A continuous‐flow, multistep microchemical synthesis of carbamates starting from aqueous azide and organic azoyl chloride by using the Curtius rearrangement reaction is ...described. The procedure involves three reaction steps and two separation steps (one gas–liquid and one liquid–liquid). Formation of a microreactor network for parallel synthesis of analogous compounds is also demonstrated.
A batch-type open cycle heat pump dryer has been numerically simulated to study the energy and exergy performances using various low-GWP refrigerants (R290, R600, R600a, R32, R152a, R1234yf, ...R1234ze(E)) as a substitute of R134a. Effects of air inlet conditions, drying time, and material moisture content on the coefficient of performance, moisture extraction rate, specific moisture extraction rate, specific energy consumption, drying efficiency, exergy destruction, and exergy efficiency have been discussed. Results show that moisture extraction rate is maximum for R32, specific moisture extraction rate is maximum for R1234ze(E), specific energy consumption is minimum for R152a, drying efficiency is maximum for R152a (average value is 29.74%), and total exergy destruction is minimum for R1234ze(E) for the same total energy input and air inlet velocity of 2 kW and 2 m/s, respectively. Specific moisture extraction rate increases with air inlet velocity. The present study reveals that R152a may be a potential substitute of R134a for heat pump dryer by considering performances as well as environmental and personal safeties.
Individual Alzheimer's disease (AD) patients have been shown to have structurally distinct amyloid-β (Aβ) aggregates, including fibrils, in their brain. These findings suggest the possibility of a ...relationship between AD progression and Aβ fibril structures. Thus, the characterization of the structural dynamics of Aβ could aid the development of novel therapeutic strategies and diagnosis. Protein structure and dynamics have typically been studied separately. Most of the commonly used biophysical approaches are limited in providing substantial details regarding the combination of both structure and dynamics. On the other hand, high-speed atomic force microscopy (HS-AFM), which simultaneously visualizes an individual protein structure and its dynamics in liquid in real time, can uniquely link the structure and the kinetic details, and it can also unveil novel insights. Although amyloidogenic proteins generate heterogeneously aggregated species, including transient unstable states during the aggregation process, HS-AFM elucidated the structural dynamics of individual aggregates in real time in liquid without purification and isolation. Here, we review and discuss the HS-AFM imaging of amyloid aggregation and strategies to optimize the experiments showing findings from Aβ and amylin, which is associated with type II diabetes, shares some common biological features with Aβ, and is reported to be involved in AD.
The absence of detergent and curvature makes nanodiscs excellent membrane mimetics. The lack of structural and mechanistic model of polymer-encapsulated lipid nanodiscs limits their use in the study ...of the structure, dynamics, and functions of membrane proteins. In this study, we parameterized and optimized the coarse-graining (CG) bead mapping for two differently charged and functionalized copolymers, containing styrene–maleic acid (SMAEA) and polymethacrylate (PMAQA), for the Martini force-field framework and showed nanodisc formation (<8 nm diameter) on a time scale of tens of microseconds using molecular dynamics (MD) simulations. Structural models of ∼2.0 or 4.8 kDa PMAQA and ∼2.2 kDa SMAEA polymer-based lipid nanodiscs highlight the importance of the polymer chemical structure, size, and polymer–lipid ratio in the optimization of the nanodisc structure. The ideal spatial arrangement of polymers in nanodiscs, nanodisc size, and thermal stability obtained from our MD simulation correlates well with the experimental observations. The polymer–nanodiscs were tested for the reconstitution of single-pass or multipass transmembrane proteins. We expect this study to be useful in the development of novel polymer-based lipid nanodiscs and for the structural studies of membrane proteins.
An increasing number of human diseases has been shown to be linked to aggregation and amyloid formation by intrinsically disordered proteins (IDPs). Amylin, amyloid-β, and α-synuclein are, indeed, ...involved in type-II diabetes, Alzheimer’s, and Parkinson’s, respectively. Despite the correlation of the toxicity of these proteins at early aggregation stages with membrane damage, the molecular events underlying the process is quite complex to understand. In this study, we demonstrate the crucial role of free lipids in the formation of lipid–protein complex, which enables an easy membrane insertion for amylin, amyloid-β, and α-synuclein. Experimental results from a variety of biophysical methods and molecular dynamics results reveal that this common molecular pathway in membrane poration is shared by amyloidogenic (amylin, amyloid-β, and α-synuclein) and nonamyloidogenic (rat IAPP, β-synuclein) proteins. Based on these results, we propose a “lipid-chaperone” hypothesis as a unifying framework for protein–membrane poration.
Polymethacrylate-copolymer (PMA) encased lipid-nanodiscs (∼10 nm) and macro-nanodiscs (>15 nm) are used to study Aβ1-40 aggregation. We demonstrate that PMA-nanodiscs form a ternary association with ...Aβ and regulate its aggregation kinetics by trapping intermediates. Results demonstrating the reduced neurotoxicity of nanodisc-bound Aβ oligomers are also reported.
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