Microscopic Particles Research Articles

Tangleoids with quantum field theories in biosystems

Abstract The open question whether quantum field theories can be used in biological systems will be addressed in this study. Quantum effects were reported for certain biological systems like the magnetic orientation sense in migratory birds. In quantum field theories it is possible to derive effective quantum field theories with welded tangleoids including braid relations that describe composite particles based on the dynamics of microscopic particle where these composite particles are made of. We observe that the generators of the tangleoid category that will depict the Feynman graphs are X X for a scattering vertex. This arises after carrying out the integral over bosonic fields A μ {A}_{\mu } in the partition function (D) that will lead to an four-valent interaction vertex generated by a quartic term in the fermionic fields. With X + {X}_{+} and X − {X}_{-} we will depict order changes like that regarding time orderings. Ordinary propagators are depicted by ∪ \cup and ∩ \cap . Finally, the generators ! \! and ¡ \hspace{0.1em}\text{¡}\hspace{0.1em} come into play if other foreign fields are picked up.

Effects of prepulse on hot electron emission from mesoscopic particles

In this paper we make an attempt to study the effect of a nanosecond prepulse on electron acceleration from microscopic solid particles. While standard scaling laws predict temperatures of ∼50 keV, our investigations showed an anomalous enhancement ( ∼200 keV) in electron temperatures from microscopic solids subjected to intense laser fields. Conventional isotropic expansion of the plasma target as a result of pre-pulse interaction is unable to explain the enhancement, prompting an experimental inquiry into the expansion form. Tentacle-like structures emerging from the spherical plasma are detected as an outcome of the pre-pulse interaction, with the region between the tentacles being targeted by the main laser pulse. We resort to PIC simulations to understand and predict the exact plasma condition that exists in this region. In this paper, we study a series of approximate pre-plasma conditions, particle shapes, and electron densities, examining them for their role in electron acceleration from this extended over-critical plasma target.

Dynamic simulation of unsteady Casson–Carreau fluid flow considering temperature-dependent variable-properties and thermo-solutal mixed convection over flat and slendering sheets

The present investigation delves into the intricate interplay between surface effects and fluid dynamics, focusing on the flow characteristics of Casson and Carreau fluids endowed with temperature-dependent thermophysical properties. Specifically, the study explores the ramifications of radiative, mixed convection, and magnetized processes on heat and mass transfer phenomena. A comprehensive mathematical model is developed to analyze the behavior of Casson–Carreau fluids in conjunction with microscopic particles and gyrotactic microorganisms over both flat and slender surfaces. Leveraging similarity transformations, the governing equations are transformed into dimensionless form, facilitating numerical solutions using the bvp5c solver in MATLAB. The ensuing numerical and graphical analyses elucidate key physical quantities, including local skin friction coefficients, gyrotactic microorganism density, Nusselt number, and Sherwood number, across a spectrum of physical parameters. Notably, the investigation underscores the profound influence of flat surfaces on flow patterns and highlights the heightened consumption of fluid particles with increasing variable diffusivity and thermal conductivity. Moreover, enhanced values of parameters such as variable motile microorganism diffusion coefficient, Brownian motion parameter, and temperature-dependent thermal conductivity parameter are found to augment the Nusselt number, indicative of intensified heat transfer rates. This research underscores the imperative of comprehending the intricate dynamics of fluid flow and heat transfer, offering actionable insights for enhancing engineering designs and addressing multifaceted challenges across domains encompassing chemical engineering, environmental science, and biomedical applications.

The Potential of Nano Pharmaceuticals to Change the Paradigm of Brain Tumor Therapy: A State-of-the-Art Review.

Central nervous system tumors are abnormal proliferations of neuronal cells within the brain and spinal cord. They can be primary or secondary and place a heavy financial, psychological, and physical burden on individuals. The highly selective blood-brain barrier, which only permits specific molecules to flow into the brain parenchyma, inhibits the efficacy of pharmacological medicines. Treatment options include surgery, chemoradiotherapy, and targeted therapy. Despite advances in therapy over the past few decades, the overall morbidity and mortality rates are still high, emphasizing the need for improved therapeutic choices to improve survival and quality of life further. Nano pharmaceuticals have demonstrated encouraging outcomes in in vivo trials using microscopic particles to enhance bioavailability and selectivity. The most successful clinical results to date have been achieved by liposomes, extracellular vesicles, and biomimetic nanoparticles; nevertheless, clinical trials are required to confirm their safety, efficacy, affordability, longterm impact, and success in patients from various demographics. Nano pharmaceuticals have the potential to change the paradigm of therapy for brain tumors, allowing better outcomes as primary and adjunctive therapy.

Microplastic Content in Fish and Sea Water at Air Tawar Coast, Padang City, Indonesia

Every year, millions of tons of plastic contaminate marine ecosystems, disrupting the natural balance and endangering marine life. Marine debris, especially plastic, is exposed to sunlight and repeated physical activities in the ocean, eventually breaking down into microscopic particles known as microplastics. This research aims to identify the presence of microplastics in fish and seawater at Air Tawar Coast, Padang City, Indonesia, based on their shapes, colors, and sizes. Seawater samples were collected at 3 stations using purposive random sampling along the direction of net trawling. Water samples were collected using a plankton net and filtered horizontally at the sea surface. Fish samples were obtained from the catches of fishermen, using trawl net (maelo pukek). The fish sampled were Selar and Kembung fish. Microplastics found in seawater and fish exhibited various shapes, including fibers, films, fragments, and pellets, with pellets and granules being the most dominant shapes. The colors of microplastics found in this study were black, brown, red, orange, blue, yellow, green, and purple, with dark colors (black and brown) being the most dominant. The abundance of microplastics at station 1 was 140.12 particles/m3, at station 2 was 151.27 particles/m3, and at station 3 was 129.61 particles/m3. The number of microplastic particles found in Kembung was higher than in Selar. On average, Selar fish contained 228 particles/individual, while Kembung fish contained an average of 267.5 particles/individual. The smallest particle size was found in pellet form, with a size of 8.12 µm, while the largest particle size was found in film form, measuring 174.56 µm.

Gravity-induced entanglement between two massive microscopic particles in curved spacetime: II. Friedmann–Lemaître–Robertson–Walker universe

In our previous work (Zhang and Shu in Eur Phys J. C 84(3):256, 2024), we have explored quantum gravity induced entanglement of masses (QGEM) in curved spacetime, observing entanglement formation between particles moving along geodesics in a Schwarzschild spacetime background. We find that long interaction time induces entanglement, even for particles with microscopic mass, addressing decoherence concerns. In this work, we build upon our previous work (Zhang and Shu 2024) by extending our investigation to a time-dependent spacetime. Specifically, we explore the entanglement induced by the mutual gravitation of massive particles in the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. With the help of the phase shift and the QGEM spectrum, our proposed scheme offers a potential method for observing the formation of entanglement caused by the quantum gravity of massive particles as they propagate in the FLRW universe. Consequently, it provides insights into the field of entanglement in cosmology.

Bejan number and entropy generation analysis of unsteady MHD non-Newtonian micropolar squeezed trihybrid nanofluid flow

Microscopic particles have incredible thermal conductivity making them essential in nanotechnology, electronics, materials science and heat exchangers. For suitable optimization of thermic engineering structure, thermal transportation has to increased but minimized the entropy generation. One of the basic reasons for the developing interest in tri hybrid nanofluids is its unique ability to increase thermal characteristics, that is very useful in numerous heat exchangers. Three distinct nanosized particles, namely silver, gold and diamond are considered with water as a base liquid. A set of dimensionless ODE’s are solved numerically by Bvp4c technique. The results of prominent parameters are elaborated and graphs are presented for velocity profile, entropy profile, Bejan and temperature profiles. Moreover, present result is compared with the literature and found a good agreement. It is observed that the Bejan number and entropy generation shows the opposite behavior for higher values of Casson and magnetic parameter. Further, it is noted that at the lower disk, squeezed Reynold number increases the skin friction coefficient and opposite trend noted against the upper disk. Temperature profile shows increasing trend for higher values of Eckert number. It is also noted that both velocities, temperature, entropy and Bejan number profiles for tri-hybrid nanofluid flow attains maximum values as compared to bi-hybrid and mono nanoparticles.

An investigation of the filtration performance and mechanism of oil-solid mixed particles on filter materials with different wettability

In the process of air filtration, filter materials may encounter oil-solid mixed particles from various sources such as industry and household, and the influence of filter material with different wettability on the filtration performance of oil-solid mixed particles has not been fully reported. The objective of this study was to prepare filter materials with varying wettability properties and investigate their filtration performance for oil-solid mixed particles with diverse oil contents. In this study, four filter materials were prepared using the impregnation method, exhibiting 0° (superoleophilic), 46° (oleophilic), 90° and 122° (oleophobic) oil contact angles. The oil-solid mixed particles with varying oil contents were loaded on the four different filter materials. The loading behavior of the filter materials was characterized from two aspects: macroscopic loading behavior (changes in pressure drop and DHC) and microscopic particle deposition behavior. The results demonstrated that, under the conditions of 25% and 50% oil content, the enhanced liquid bridge force between the oil-solid mixed particles on the oleophobic filter material facilitated the formation of a loose and porous cake layer structure compared with other filter materials, resulting in a lower growth rate of pressure drop and a higher dust holding capacity (DHC). However, in 75% and 100% oil content environments, the superoleophilic filter material owned a remarkably high affinity for oil particles compared with other filter materials, leading to the gradual formation of an oil film structure on the filter material, yielding lower the growth rate of pressure drop and higher DHC. These findings shed light on the mechanism of particle deposition under diverse filtration conditions and are applicable to the filtration of various oil-solid mixed particles over a wide range of oil contents.

Resident macrophages in kidney medulla are critical in cleaning intratubular sedimentary particles

During the passage of the glomerulus filtrate through the renal tubular system, various microscopic sedimentary particles, including mineral crystals resulting from urine concentration, are generated. Dislodging these particles in the intratubular compartment is critical to ensure free flow of filtrate and the final formation of urine. However, it is generally assumed that particle removal is solely attributed to urine flush and whether there is other devoted mechanism is unknown. In this study, we uncovered that most macrophages in the kidney medulla of mice constitutively formed transepithelial protrusions and were “sampling” urine contents, as revealed by high-resolution confocal microscopy. This phenomenon was less pronounced in the cortex. The transepithelial protrusions of medulla macrophages were formed in a transcellular route instead of between epithelial cells, so the overall junctional architecture of tubular epithelium was intact. Juxtatubular macrophages were effcient in sequestering and phagocytosing intraluminal particles through their transepithelial protrusions, and would make transmigration to the tubule lumen to "escort" the excretion of sediment particles, as documented by live two-photon microscopy recording. In accordance, abundant particle-carrying macrophages could be detected in the urine. As such, specifically depleting renal macrophages precipitated kidney stone formation in a hyperoxaluria model. Moreover, naïve mice with underrepresentation of renal macrophages were prone to developing various intratubular sediments. RNA-seq analyses unveiled that medulla macrophages were enriched with genes associated with cell adhesion relative to cortex macrophages. Mechanistically, we found that integrin β1-mediated ligation to the tubular epithelium was crucial to the transepithelial behaviors of medulla macrophages, as evidenced by both pharmacological and genetic approaches. This study unveils a previously unappreciated role of renal medulla macrophages in keeping the tubular system unobstructed by removing intratubular particles. These findings may pave way for developing novel therapeutics for nephrolithiasis. National Natural Science Foundation of China (32170894, 31970898 and 82170441) and the Natural Science Foundation of Zhejiang Province (LZ22C080001). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Induced-charge electrophoresis of a tilted metal nanowire near an insulating wall.

Electric fields are commonly used to control the orientation and motion of microscopic metal particles in aqueous suspensions. For example, metallodielectric Janus spheres are propelled by the induced-charge electro-osmotic flow occurring on their metallic side, the most common case in electrokinetics of exploiting symmetry breaking of surface properties for achieving net particle motion. In this work, we demonstrate that a homogeneous metal rod can translate parallel to a dielectric wall as a result of the hydrodynamic wall-particle interaction arising from the induced-charge electro-osmosis on the rod surface. The applied electric field could be either dc or low-frequency ac. The only requirement for a nonvanishing particle velocity is that the axis of the rod be inclined with respect to the wall, i.e., it cannot be neither parallel nor perpendicular. We show numerical results of the rod velocity as a function of rod orientation and distance to the wall. The maximum particle velocity is found for an orientation of between ∼30^{∘} and ∼50^{∘}, depending on the position and aspect ratio of the cylinder. Particle velocities of up to tens of µm/s are predicted for typical conditions in electrokinetic experiments.

High throughput clogging free microfluidic particle filter by femtosecond laser micromachining.

In recent decades, driven by the needs of industry and medicine, researchers have been investigating how to remove carefully from the main flow microscopic particles or clusters of them. Among all the approaches proposed, crossflow filtration is one of the most attractive as it provides a non-destructive, label-free and in-flow sorting method. In general, the separation performance shows capture and separation efficiencies ranging from 70% up to 100%. However, the maximum flow rate achievable (µL/min) is still orders of magnitude away from those suitable for clinical or industrial applications mainly due to the low stiffness of the materials typically used. In this work, we propose an innovative hydrodynamic-crossflow hybrid filter geometry, buried in a fused silica substrate by means of the femtosecond laser irradiation followed by chemical etching technique. The material high stiffness combined with the accuracy of our manufacturing technique allows the 3D fabrication of non-deformable channels with higher aspect ratio posts, while keeping the overall device dimensions compact. The filter performance has been validated through experiments with both Newtonian (water-based solution of microbeads) and non-Newtonian fluids (blood), achieving separation efficiencies of up to 94% and large particles recovery rates of 100%, even at very high flow rates (mL/h).

Programmable photoacoustic patterning of microparticles in air.

Optical and acoustic tweezers, despite operating on different physical principles, offer non-contact manipulation of microscopic and mesoscopic objects, making them essential in fields like cell biology, medicine, and nanotechnology. The advantages and limitations of optical and acoustic manipulation complement each other, particularly in terms of trapping size, force intensity, and flexibility. We use photoacoustic effects to generate localized Lamb wave fields capable of mapping arbitrary laser pattern shapes. By using localized Lamb waves to vibrate the surface of the multilayer membrane, we can pattern tens of thousands of microscopic particles into the desired pattern simultaneously. Moreover, by quickly and successively adjusting the laser shape, microparticles flow dynamically along the corresponding elastic wave fields, creating a frame-by-frame animation. Our approach merges the programmable adaptability of optical tweezers with the potent manipulation capabilities of acoustic waves, paving the way for wave-based manipulation techniques, such as microparticle assembly, biological synthesis, and microsystems.

Quantum statistical mechanics from a Bohmian perspective

We develop a general formulation of quantum statistical mechanics in terms of probability currents that satisfy continuity equations in the multi-particle position space, for closed and open systems with a fixed number of particles. The continuity equation for any closed or open system suggests a natural Bohmian interpretation in terms of microscopic particle trajectories, that make the same measurable predictions as standard quantum theory. The microscopic trajectories are not directly observable, but provide a general, simple and intuitive microscopic interpretation of macroscopic phenomena in quantum statistical mechanics. In particular, we discuss how various notions of entropy, proper and improper mixtures, and thermodynamics are understood from the Bohmian perspective.

Preparation of VC nanoliposomes by high pressure homogenization: Process optimization and evaluation of efficacy, transdermal absorption, and stability

Vitamin C (VC) possesses antioxidant and whitening effects. However, its effectiveness is hindered by challenges such as instability, impaired solubility, and limited bioavailability hinder. In this study, VC was encapsulated in nanoliposomes by primary emulsification and high-pressure homogenization. The VC nanoliposomes were comprehensively characterized for their microscopic morphology, particle size, polydispersity index (PDI), and encapsulation efficiency (EE). Orthogonal experiments were designed to optimize the optimal preparation process, and the antioxidant activity, whitening efficacy, transdermal absorption, and stability of VC nanoliposomes were evaluated based on this optimized process. The findings demonstrated the high reproducibility of the optimal process, with particle size, PDI, and EE values of 113.502 ± 4.360 nm, 0.104 ± 0.010, and 56.09 ± 1.01 %, respectively. Differential scanning calorimetry analysis showed effective encapsulation of VC nanoliposomes with better thermal stability than aqueous VC solution. Besides, the VC nanoliposomes demonstrated excellent antioxidant and whitening effects in efficacy experiments, stronger skin permeability in transdermal experiments and fluorescence tracking. Furthermore, storage stability tests indicated that the VC in nanoliposomes remained relatively stable after 60 days of storage. These findings highlighted the potential use of VC nanoliposomes in a wide range of applications for the cosmetic market, especially in the development of ingredients for skin care products.

Colorimetric and fluorometric determination of uric acid by a suspension-based assay using enzyme-immobilized micro-sized particles.

Daily monitoring of serum uric acid levels is very important to provide appropriate treatment according to the constitution and lifestyle of individual hyperuricemic patients. We have developed a suspension-based assay to measure uric acid by adding a sample solution to the suspension containing micro-sized particles immobilized on uricase and horseradish peroxidase (HRP). In the proposed method, the mediator reaction of uricase, HRP, and uric acid produces resorufin from Amplex red. This resorufin is adsorbed onto enzyme-immobilized micro-sized particles simultaneously with its production, resulting in the red color of the micro-sized particles. The concentration of resorufin on the small surface area of the microscopic particles achieves a colorimetric analysis of uric acid with superior visibility. In addition, ethanol-induced desorption of resorufin allowed quantitative measurement of uric acid using a 96-well fluorescent microplate reader. The limit of detection (3σ) and RSD (n = 3) were estimated to be 2.2 × 10-2μg/mL and ≤ 12.1%, respectively. This approach could also be applied to a portable fluorometer.

Nanoscopic Interfacial Hydrogel Viscoelasticity Revealed from Comparison of Macroscopic and Microscopic Rheology.

Deviations between macrorheological and particle-based microrheological measurements are often considered to be a nuisance and neglected. We study aqueous poly(ethylene oxide) (PEO) hydrogels for varying PEO concentrations and chain lengths that contain microscopic tracer particles and show that these deviations reveal the nanoscopic viscoelastic properties of the particle-hydrogel interface. Based on the transient Stokes equation, we first demonstrate that the deviations are not due to finite particle radius, compressibility, or surface-slip effects. Small-angle neutron scattering rules out hydrogel heterogeneities. Instead, we show that a generalized Stokes-Einstein relation, accounting for an interfacial shell around tracers with viscoelastic properties that deviate from bulk, consistently explains our macrorheological and microrheological measurements. The extracted shell diameter is comparable to the PEO end-to-end distance, indicating the importance of dangling chain ends. Our methodology reveals the nanoscopic interfacial rheology of hydrogels and is applicable to different kinds of viscoelastic fluids and particles.

Lack-of-fit reduction in non-equilibrium thermodynamics applied to the Kac–Zwanzig model

Abstract Even when microscopic particle dynamics is purely mechanistic and thus reversible, the behavior of macroscopic systems composed of those particles is irreversible. In other words, effectively irreversible behavior emerges out of purely reversible dynamics when we do not observe all degrees of freedom of the detailed dynamics. But how can we find the irreversible macroscopic evolution equations when we only know the reversible microscopic equations? Using the so-called lack-of-fit reduction, which gives the reduced evolution as a sum of Hamiltonian and gradient dynamics, we reduce the purely Hamiltonian Kac–Zwanzig model to a set of irreversible evolution equations with no fitting parameters.

Microplastic contamination in filter-feeding oyster Saccostrea cuccullata: Novel insights in a marine ecosystem

Microplastic (MP) pollution has become a pressing global concern. Oysters are well-known filter feeders who ingest food by filtering microscopic particles suspended in the surrounding water. Along with organic matter, filter-feeding also causes accidental ingestion of MP by oysters. Hence, the aim of the current investigation is to understand the MP contamination in filter-feeding oysters. A total of 500 specimens of oyster Saccostrea cuccullata collected from the intertidal zone of five sampling locations on the Gujarat coast, India. Specimens underwent analysis following established protocols. Each specimen was found to exhibit MP contamination, showing an abundance of 2.72 ± 1.98 MPs/g. A negative relationship was found between shell length and MP abundance. Predominantly, fibers were documented across all study sites. Black, blue, and red-colored MPs with 1–2 mm sizes were most dominant. MP polymer composition was identified as polyethylene terephthalate and polypropylene. Findings provide baseline information on levels of MPs contamination, which can be used to monitor future effects of MP pollution.

Study on Plugging Microfracture by Using High-Temperature Emulsified Bitumen

A new kind of modified emulsified bitumen used to plug a microcrack was studied. The sizes of high-temperature emulsified bitumen were fit for the sizes of the microcrack, which were approved by the scanning electron microscope and laser particle size analyzer. Some tests have been designed to demonstrate that the polymer could be used to promote the softening point of modified asphalt, and the high-temperature emulsified bitumen has also shown an excellent performance in terms of static filtration, the viscous coefficient, and extreme pressure lubrication, as well as to inhibit ting shale expansion. The permeability recovery could reach 88.26%, which meets the specification requirements. The mud cake, which was formed by high-temperature emulsified bitumen as an additive, was thin, tough, and dense, which was proved by the scanning electron microscope. The process used to obtain this additive was simple, and the performance of the plugging microfracture was excellent, so this kind of plugging agent could have a better application future.

New computational method for calculating of water droplet–clay contact angles: Based on molecular dynamics

The measurement of the water contact angle (θ) on the surface of clay minerals poses a significant challenge due to their microscopic particle sizes ranging from micrometers to nanometers and their extensive specific surface areas. We introduce an advanced computational framework based on molecular dynamics simulations. This framework leverages the coordination number (CN) differences of the water molecules and effectively eliminates the gaseous water molecules in the droplet equilibrium system. Additionally, our framework uses an alpha-shaped probe ball to accurately determine the three-dimensional (3D) coordinates of the droplet interface and utilizes a feed-forward neural network (FFNN) to optimize the objective function of the 3D-interface; this ensures highly accurate characterization of the interface contour and an accurate computation of θ. Our approach exhibits outstanding performance in typical clay mineral surface-water wetting systems; it significantly overcomes the limitations of the transformed cylindrical coordinate system algorithm and accurately captures the wettability variations under complex environmental conditions. This new θ computational framework provides crucial assistance for the in-depth exploration of the wettability characteristics of clay minerals in complex environments.