External Particles Research Articles

Covalent Organic Frameworks with Constrained Palladium Nanoclusters Lock the Enol-Keto Tautomerism Enhancing Hydrogen Peroxide Photosynthesis.

The production of hydrogen peroxide from natural seawater is green and sustainable. However, the efficiency of photocatalytic hydrogen peroxide production is low due to the degradation and poisoning of photocatalysts by the abundant ions in natural seawater. Precisely controlling the structure of photocatalysts to enhance their corrosion resistance and minimize the impact of external particles is a challenging task. Here, a novel molecular engineering strategy is reported in which confined Pd nanoclusters locked keto structures to enhance photocatalytic hydrogen peroxide production. Both experimental and theoretical findings reveals that Pd nanoclusters, when confined within a keto structure, not only bolster the stability of the photocatalyst but also augment the efficiency of photogenerated charge carriers' separation and transport. This dual enhancement significantly boosts the photocatalytic performance for hydrogen peroxide synthesis. One of the photocatalysts, TAPT-2KtTb Pd COF, exhibits an impressive photocatalytic hydrogen peroxide production rate of 2676.3µmol g-1 h-1, which is one of the highest values reported so far. Integral photocatalyzed H2O2 synthesis using confined Pd nanoclusters locked keto conformation COF provides a new insight for developing innovative photocatalysts for H2O2 synthesis.

Evaluation of lead levels in children with chronic constipation.

This study aimed to assess blood and hair lead levels (BLL and HLL) in children with chronic constipation and compare them to healthy children; and investigated lead exposure's role in the etiology of constipation. It also explored the correlation between BLL and HLL. The study included 84 constipated children aged 3-18 years as the case group and an equal number of constipation-free children as controls. Organic diseases were ruled out through history-taking, physical exams and laboratory tests. Blood and hair samples were collected and analyzed for lead levels using standardized methods. The constipated children group had significantly higher BLL (3.66 µg/dL) compared to the control group (1.61 µg/dL) with no significant HLL difference. Additionally, 48.8% of constipated children exceeded the reference value of 3.5 μg/dL, in contrast to 4.8% of the control group. BLL was unaffected by gender and age, while HLL were higher in girls and low ages. No significant correlation existed between BLL and HLL. The age of the housing showed a positive correlation with higher BLL and HLL. Lead exposure sources like drinking water, home renovation history, parental smoking, or nearby industrial facilities showed no significant relationships with lead levels. Understanding the constipation-lead exposure link is crucial for prevention and intervention. HLL may vary with gender and age due to external lead particles, which is why BLL continues to be a more reliable measure. Healthcare providers should remember to investigate lead exposure risk factors in constipation patients and test BLL when necessary.

Momentum shift and on-shell constructible massive amplitudes

We construct tree-level amplitude for massive particles using on-shell recursion relations based on two classes of momentum shifts: an all-line transverse shift that deforms momentum by its transverse polarization vector, and a massive Britto-Cachazo-Feng-Witten-type shift. We illustrate that these shifts allow us to correctly calculate four-point and five-point amplitudes in massive QED, without an ambiguity associated with the contact terms that may arise from a simple “gluing” of lower-point on-shell amplitudes. We discuss various aspects and applicability of the two shifts, including the large-z behavior and complexity scaling. We show that there exists a “good” all-line transverse shift for all possible little group configurations of the external particles, which can be extended to a broader class of theories with massive particles such as massive QCD and theories with massive spin-1 particles. The massive Britto-Cachazo-Feng-Witten-type shift enjoys more simplicity, but a “good” shift does not exist for all the spin states due to the specific choice of spin axis. Published by the American Physical Society 2024

Eikonal amplitudes on the celestial sphere

Celestial scattering amplitudes for massless particles are Mellin transforms of momentum-space scattering amplitudes with respect to the energies of the external particles, and behave as conformal correlators on the celestial sphere. However, there are few explicit cases of well-defined celestial amplitudes, particularly for gravitational theories: the mixing between low- and high-energy scales induced by the Mellin transform generically yields divergent integrals. In this paper, we argue that the most natural object to consider is the gravitational amplitude dressed by an oscillating phase arising from semi-classical effects known as eikonal exponentiation. This leads to gravitational celestial amplitudes which are analytic, apart from a set of poles at integer negative conformal dimensions, whose degree and residues we characterize. We also study the large conformal dimension limits, and provide an asymptotic series representation for these celestial eikonal amplitudes. Our investigation covers two different frameworks, related by eikonal exponentiation: 2 → 2 scattering of scalars in flat spacetime and 1 → 1 scattering of a probe scalar particle in a curved, stationary spacetime. These provide data which any putative celestial dual for Minkowski, shockwave or black hole spacetimes must reproduce. We also derive dispersion and monodromy relations for these celestial amplitudes and discuss Carrollian eikonal-probe amplitudes in curved spacetimes.

Dual Grain Refinement Effect for Pure Aluminum with the Addition of Micrometer-Sized TiB2 Particles.

The inefficiency of grain refinement processes has traditionally been attributed to the limited utilization of heterogeneous nucleation particles within master alloy systems, resulting in the formation of abundant inactive particles. This study aims to investigate the alternative influences of particles by incorporating external micrometer-sized TiB2 particles into the grain refinement process. Through a series of experiments, the refinement efficiency, grain refinement mechanism, and resultant microstructure of TiB2 particle-induced grain refinement specimens are comprehensively examined using various microscopy and analytical techniques, including polarization microscopy (OM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). Our findings demonstrate a direct correlation between increased levels of TiB2 particles and enhanced grain refinement efficiency. Moreover, the microstructure analysis reveals the distribution of TiB2 particles along grain boundaries, forming a coating due to self-assembly phenomena, while regions with a lower particle content may exhibit irregular grain structures. DSC analysis further confirms reduced undercooling, indicating the occurrence of heterogeneous nucleation events. However, TEM observations suggest that heterogeneous nucleation is not significantly influenced by the growth restriction factor attributed to TiAl3 2DC compounds. The grain refinement mechanism involving TiB2 particles is elucidated to entail both heterogeneous nucleation and physical growth restriction effects. Specifically, a reduction in average grain size is attributed not only to heterogeneous nucleation but also to the physical growth restriction effect facilitated by the TiB2 particle coating. This study offers insights into leveraging particles that do not participate in heterogeneous nucleation within master alloy-based grain refinement systems.

A shrapnel migration from a peripheral vein to the right ventricle: case report

Abstract Background Foreign bodies that migrate into the heart may include medical devices dislodged from their original location or, rarely, external particles (shrapnel and other foreign bodies) that penetrate the vein, remain intraluminal, and migrate via the venous blood flow to the right heart. Most reported entry sites of these external foreign bodies were in the torso, thigh, or neck; none of them penetrated through a distal extremity of the body. We report a case where shrapnel was found in the right ventricle (RV) following penetrating injury to the hand. Case summary An otherwise healthy 24-year-old man presented with an isolated shrapnel injury to his right hand and forearm from an explosion trauma. Computed tomography demonstrated multiple small metal objects in the forearm, hand, and wrist. Additionally, a 3 × 3.5 mm metal object was found in the RV, consistent with a metal shrapnel embolus from the forearm. Echocardiography indicated the fragment to be in a fixed position within the RV, without any additional pathology. Discussion Even shrapnel that penetrates through the hand or forearm may migrate to the heart. In this case, following a multidisciplinary discussion, a conservative approach was recommended based on the following condition: lack of symptoms, small size of the foreign body, no obstruction of venous effluent, low risk of significant embolization to the pulmonary vasculature, absence of fever or endocarditis, no current evidence or risk of valve dysfunction, and no myocardial irritation indicated by arrhythmia. The patient was instructed to avoid magnetic resonance imaging scans.

Raman spectroscopy capabilities for advanced semiconductor technology devices

In semiconductor processing and metrology, Raman spectroscopy is a valuable characterization tool because of its nondestructive nature, high throughput, and versatility in terms of parameter sensitivity. However, with the miniaturization of semiconductor devices, the inherent diffraction limit of the optical technique becomes a roadblock. In order to re-enable the strengths of Raman spectroscopy at the nanometer scale, we exploit polarization-induced enhancement effects that focus the excitation light into the region of interest, without the need for external probes or particles. This allows the detection of structures with dimensions far smaller than the excitation wavelength, unlocking the strengths of Raman spectroscopy at the nanoscale for, e.g., stress and composition measurements. Moreover, under these conditions the experiment probes the totality of the materials stack and we show how this transforms the technique into a volumetric and geometric measurement. The result is a completely new application domain for Raman spectroscopy as a critical dimensional metrology toolkit for a wide variety of semiconducting and metallic materials.

The neutrino force in neutrino backgrounds: Spin dependence and parity-violating effects

The neutrino force results from the exchange of a pair of neutrinos. A neutrino background can significantly influence this force. In this work, we present a comprehensive calculation of the neutrino force in various neutrino backgrounds with spin dependence taken into account. In particular, we calculate the spin-independent and spin-dependent parity-conserving neutrino forces, in addition to the spin-dependent parity-violating neutrino forces with and without the presence of a neutrino background for both isotropic and anisotropic backgrounds. Compared with the vacuum case, the neutrino background can effectively violate Lorentz invariance and lead to additional parity-violating terms that are not suppressed by the velocity of external particles. We estimate the magnitude of the effect of atomic parity-violation experiments, and it turns out to be well below the current experimental sensitivity.

A study on the evolution of microstructure of soil-rock mixtures based on the electrochemical conductive paths model under different rock and moisture content conditions

ABSTRACT To further improve the understanding of the evolution law of the microstructure of SRM in road engineering under moisture and rock content, the electrochemical impedance spectroscopy test under different moisture and rock conditions was carried out. This paper proposed an electrochemical model of different conductive paths based on different cementation states. The impact of rock and moisture content on the characteristic parameters of the conductive path model was analyzed. The results indicated the impedance spectrum curves became more pronounced with the continuous decrease in moisture content and increase in rock content. There was a well-defined exponential relationship between total impedance and both moisture and rock content. The total impedance decreased continuously with increasing moisture content and increased with increasing rock content. The characteristic parameters had practical significance in representing the microscopic structure. The moisture content primarily influenced the variation trends of the representation parameters by altering the channel width, length, and quantity of the continuous pore water solution pathways and the discontinuous rock-soil bonded bodies. The rock content affected the changes by compressing the external and internal pore water solution and soil particles, altering the compression and support between the continuous pore water solution pathways and the block rock framework.

Characterization of HDPE microparticles in sludge aerobic digestion and their influence on the process

The occurrence of microplastics (MPs) in wastewater has been studied in the last years. The high efficiency of their removal from wastewater is linked to their transfer to the sludge. In this work, the effect of high-density polyethylene (HDPE) on aerobic digestion was evaluated and these MPs were monitored, characterizing them by three different techniques. Two parallel batch digesters were monitored. AD-Control (meaning Aerobic Digester) operated as a reference, with no external HDPE particles, whereas these polymeric fragments were introduced to the second aerobic digester (AD-HDPE) using ring pulls as microplastic support. FTIR, Raman spectroscopies and fluorescence analysis of these microparticles showed some relevant results that should be highlighted. Higher fluorescence appeared after 7 days in the digester. It coincided with an increase of active volatile suspended solids (AVSS) in the AD-HDPE, which means that an increase of the microbial activity took place. Despite the presence of HDPE particles in the sludge, the digester performance was not compromised. Besides, the HDPE particles did not affect the microbial diversity (Shannon index) of the bacterial community at the end of the experiment compared to the bacterial community of the aerobic digester control tank. Based on the analysis of the relative abundances of microbial taxa, it was concluded that HDPE had selective effects on sludge microbial community, increasing the relative abundance of Bacteroridota phylum.

The constructive method for massive particles in QED

The constructive method of determining amplitudes from on-shell pole structure has been shown to be promising for calculating amplitudes in a more efficient way. However, challenges have been encountered when a massless internal photon is involved in the gluing of three-point amplitudes with massive external particles. In this paper, we use the original on-shell method, old-fashioned perturbation theory, to shed light on the constructive method, and show that one can derive the Feynman amplitude by correctly identifying the residue even when there is an internal photon involved.

Next-to-eikonal corrected double graviton dressing and gravitational wave observables at OG2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left({G}^2\\right) $$\\end{document}

Following a recent proposal to describe inelastic eikonal scattering processes in terms of gravitationally dressed elastic eikonal amplitudes, we motivate a collinear double graviton dressing and investigate its properties. This is derived from a generalized Wilson line operator in the worldline formalism by integrating over fluctuations of the eikonal trajectories of external particles in gravitationally interacting theories. The dressing can be expressed as a product of exponential terms — a coherent piece with contributions to all odd orders in the gravitational coupling constant and a term quadratic in graviton modes, with the former providing classical gravitational wave observables. In particular, the coherent dressing involves Oκ3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\mathcal{O}\\left({\\kappa}^3\\right) $$\\end{document} subleading double graviton corrections to the Weinberg soft factor. We use this dressing to derive expressions for the waveform, radiative momentum spectrum and angular momentum. In a limiting case of the waveform, we derive the nonlinear memory effect resulting from the emission of nearly soft gravitons from a scattering process.

Near mass-shell double boxes

Two-loop multi-leg form factors in off-shell kinematics require knowledge of planar and nonplanar double box Feynman diagrams with massless internal propagators. These are complicated functions of Mandelstam variables and external particle virtualities. The latter serve as regulators of infrared divergences, thus making these observables finite in four space-time dimensions. In this paper, we use the method of canonical differential equations for the calculation of (non)planar double box integrals in the near mass-shell kinematical regime, i.e., where virtualities of external particles are much smaller than the Mandelstam variables involved. We deduce a basis of master integrals with uniform transcendental weight based on the analysis of leading singularities employing the Baikov representation as well as an array of complementary techniques. We dub the former asymptotically canonical since it is valid in the near mass-shell limit of interest. We iteratively solve resulting differential equations up to weight four in terms of multiple polylogarithms.

Regge constraints on local four-point scattering amplitudes of massive particles with spin

In this work, we classify all the possible local four-point couplings relevant for tree-level flat space 2 → 2 scattering of external massive particles of spin one and spin two which do not grow faster than s2 at large s and fixed t. This kinematic constraint on local growth of tree-level S-matrices is known as Classical Regge Growth criteria or CRG [1]. We first construct the spin one and spin two tree-level contact S-matrices as modules of polarisation tensors and momenta over the ring of polynomials generated by Mandelstam invariants. We then consider a general scattering process where the external scattering particles are of different masses but of same spin and constrain this space to obtain a finite number of CRG allowed local Lagrangians. Our concrete results are primarily for D ≥ 8 but the process outlined is easily generalised to lower dimensions to include low dimensional parity violating structures. The space of CRG allowed structures reduces when we specialise to identical scattering and restrict to parity even couplings in D = 4. We show that tree-level scattering amplitudes involving exchange diagrams and contact terms in de Rham-Gabadadze-Tolley massive gravity (dRGT) violate CRG unless the parameters of the theory take special values. The CRG allowed S-matrices, in the context of large N conformal field theories (CFTs), can also be interpreted as bulk AdS counterterms consistent with Chaos bound. Our classified structures therefore can be thought of as ambiguities arising in the context of conformal field theory inversion formula for four point functions of unconserved spin one and spin two operators in large N CFTs.

Understanding the Origins of Quark Charges, Quantum of Magnetic Flux, Planck’s Radiation Constant and Celestial Magnetic Moments with the 4G Model of Nuclear Charge

Introduction: In our previous published papers, considering 3 large atomic gravitational constants assumed to be associated with weak, strong and electromagnetic interactions, we have proposed the existence of a nuclear charge of magnitude, en=2.95e and developed a nuclear mass formula associated with strong and weak interactions having 4 simple terms and only one energy coefficient. Methods: Two important assumptions are that there exists a weak fermion of rest energy 585 GeV and a strong coupling constant is the squared ratio of electromagnetic charge and nuclear charge. The aim of this paper is associated with understanding the mystery of the quantum of magnetic flux, Planck’s quantum radiation constant and Reduced Planck’s constant. Proceeding further, quark charges, strong coupling constant, nuclear stability, nuclear binding energy, medium and heavy atomic X-ray levels and celestial magnetic moments can be understood in a unified approach. It may also be noted that, by considering the integral nature of elementary particle masses, it seems possible to understand the discreteness of angular momentum. Results: Considering our proposed en=2.95e=3e as a characteristic nuclear charge, it seems possible to understand the integral nature of quarks electromagnetic charge. With this idea, neutron, proton and pion decay can be understood very easily. Conclusion: In all the cases, the up quark of charge (±2e) seems to play a crucial role in the internal transformation of the down quark of charge (±e) and external observable elementary basic elementary particles. It needs further study at the fundamental level.

Wigner 6j symbols with gluon lines: completing the set of 6j symbols required for color decomposition

We construct a set of Wigner 6\U0001d457 symbols with gluon lines (adjoint representations) in closed form, expressed in terms of similar 6\U0001d457 symbols with quark lines (fundamental representations). Together with these Wigner 6\U0001d457 symbols with quark lines, this gives a set of 6\U0001d457 symbols sufficient for treating QCD color structure for any number of external particles, in or beyond perturbation theory. This facilitates a complete treatment of QCD color structure in terms of orthogonal multiplet bases, without the need of ever explicitly constructing the corresponding bases. We thereby open up for a completely representation theory based treatment of SU(N) color structure, with the potential of significantly speeding up the color structure treatment.

Recent Patents on Device or System Innovation in Pneumatic Conveying

Abstract: Coal is mostly stored in coal bunkers. As the amount of coal in the bunker increases, the concentration of coal dust inside the bunker also increases, making it susceptible to accidents such as fires and explosions. Additionally, the leakage of coal dust particles can cause significant environmental pollution in the surrounding area, leading to resource wastage. To improve energy efficiency, reduce material transport dust concentration, and protect the surrounding environment, the efficient, energy-saving, and environmentally friendly characteristics of pneumatic conveying systems are utilized. This is achieved through the use of anti-dust telescopic pipeline equipment (DTPE), which effectively prevents external dust particles from entering the telescopic pipeline, thus reducing mechanical wear. In environments with high coal dust concentration, a coal particle pneumatic conveying storage system based on DTPE is used to extend the service life of pneumatic conveying pipelines and effectively reduce the coal dust concentration within the storage bin. This study reviews the patents and research achievements of scholars in the field of pneumatic conveying and focuses on the anti-dust telescopic pipeline equipment (DTPE) and the coal particle pneumatic conveying storage system based on DTPE. Experiments using pneumatic conveying, screw conveyors, and belt conveyors are conducted to compare conveying time and efficiency. Dust reduction experiments are carried out in the coal bunker to verify the dust reduction effect of the coal particle pneumatic conveying storage system based on DTPE. The anti-dust telescopic pipeline equipment (DTPE) features a telescopic shell to protect the telescopic pipeline, effectively reducing mechanical wear caused by coal particles entering the gaps in the pipeline during pneumatic conveying. The coal particle pneumatic conveying storage system based on DTPE includes a cyclone dust removal system and a dynamic monitoring system, which monitors the temperature inside the bin and reduces the coal dust concentration, thereby minimizing the occurrence of safety accidents. Through experimental verification, the coal particle pneumatic conveying storage system based on DTPE is found to be suitable for environments with high coal dust concentrations. The anti-dust telescopic pipeline equipment (DTPE) and the coal particle pneumatic conveying storage system based on DTPE achieve the automated feeding, dust removal, return, and discharge of coal particles. They offer advantages such as high system automation, minimal environmental pollution, and high coal transport rates, providing design references for the pneumatic conveying of coal and other ore particle materials.

50.3 ps time resolution and an 11-channel time measuring chip for Topmetal detectors

The Topmetal detector, utilized in this investigation, is a direct-type CMOS pixel sensor known for its distinctive feature of employing exposed metal at the top of each pixel to directly capture external charged particles. This method generates electrical signals through the induction of charge. At present, it is mainly used in gas pixel detector(GPD) and particle beam monitoring. In this paper, we present a new front-end design aimed at enhancing the capabilities of the Topmetal pixel detector. The focus is on incorporating a Time-Digital Conversion (TDC) ASIC into the front-end, with the objective of achieving high-precision time measurement in addition to superior position resolution. The function of the TDC is achieved by the two reverse delay chains, 11 edge acquisition circuits Time-to-Amplitude Converter (TAC), analog gate, weight count module, and Wilkinson Analog-to-Digital Converter (ADC). Coarse time measurement is implemented based on a counter with a working frequency of 500 MHz, and fine time measurement is implemented by the combination of TAC and ADC. The design prototype was taped out with the GSMCR130 nm technology. Test results show that this circuit can handle up to 11 consecutive cases, with the minimum time interval of adjacent cases being 500 ps and the bin size up to 2 ps. The time measurement precision is better than 50.3 ps RMS and the PVT(Process Voltage Temperature) robustness of the input delay chain circuit is validated, showing the stable performance of the design.

High-Temperature Tribology of Selective Laser-Melted Titanium Alloys: Role of Adhesive Wear

Abstract Titanium alloys (Ti6Al4V) are emerging materials used in many engineering applications, especially aerospace, due to their strength-to-weight ratio, corrosion resistance, and high specific strength. The selective laser melting (SLM) process is vividly used to fabricate components with minimum material usage, which reduces the total weight of the product. The hard particles in the atmosphere repeatedly hit the aircraft turbine blades in a rotary motion during aircraft operations. Due to significant sliding action between articulating surfaces, these turbine blades need good wear resistance. With this motivation, rotary wear tests were performed under high vacuum at three different temperatures: room temperature, 400 °C, and 850 °C on as-built and heat-treated titanium alloy fabricated by the SLM process. The parameters like the speed, number of cycles, time, and high vacuum were considered to be constant while performing these high-temperature tribology experiments. As-built and heat-treated samples against the alumina ball resulted in lower coefficient of friction (COF) values at high temperatures compared to room temperature. In addition, adhesive wear was found to be the dominant wear mechanism at high temperatures. From the morphological studies, plowing strips, plowing ridges, and shallow grooves were significantly noticed on the worn-out surfaces of the heat-treated samples. Although low COF values were obtained at high temperatures on tested samples, higher specific wear-rates were seen in these samples due to the continuous removal of soft material.

Short communication: “Effect of dissolved hydrogen on the early corrosion behavior of 316 stainless steel in simulated PWR environments”

In simulated pressurized water reactor environments, the corrosion test on 316 stainless steel was conducted for 40 to 4000 s, with 25 and 50 cc/kg-H2O dissolved hydrogen concentrations (NH and HH). It was found that the external Fe-rich oxide particles and the inner Cr-rich layer were simultaneously formed at the beginning of corrosion. However, the first formed Cr-rich layer was mainly Cr(OH)3 in the NH condition, while Cr2O3 in the HH condition. As exposure time increased, fraction of Cr2O3 increased due to transformation from Cr(OH)3 in both conditions. In addition, for HH condition, partial transformation to FeCr2O4 was observed.