Experimental Proof Research Articles

Software Define Wide Area Network (SDWAN) network optimization analysis on radiolink-fiber optic access media migration

The development of technology in radiolink networks has grown rapidly and is suitable to be implemented on wide coverage area networks, but weather and physical environment factors greatly affect signal conditions. The background that has been stated, this study proposes migration to fiber optic access media because it is able to send data faster and is not affected by electromagnetic interference and is stable. Furthermore, this study conducted an optimization analysis on the SDWAN (Software Defined Wide Area Network) network, SDWAN functions as a firewall that can provide connectivity support and infrastructure network development in branch offices with system security in one centralized platform. The test method used in this study is a connectivity test from each remote fortigate located in the branch office. While the analysis method used is Quality of Service (QoS), which is a method to find out data delivery (Packet Loss, Delay and Jitter) using the FortiManager application, which is the analytical and experimental proof of concept of the SDWAN network model using the BGP method for auto failover testing.

Rotating Spacetime: Theory or Reality? A Concise Journey of General Relativity

The paper reviews the theoretical formulae of different astrophysical conditions to describe spacetime and connects theory with observational evidence. The spacetime is governed by gravity, which is well-explained by the theory of General Relativity. The paper starts from the simplest version of spacetime, that is, flat spacetime which has no gravitational influence. This spacetime is described by the Minkowski metric. Then the paper goes to the properties of spacetime in the presence of gravity, which creates curved spacetime. The Schwarzschild metric defines this spacetime. Although these phenomena are well-established by experimental proof, the most intricate characteristic of spacetime has not been discovered until very recently. That is the spacetime around a rotating massive body. The paper will present the mathematical expressions for describing such spacetime, the Kerr metric, and finally will end with the observational evidence of the effect of a spinning heavy body around it. Some particular exotic effects such as “frame-dragging" and “ergosphere" will be presented in brief.

Four-level diffractive photon sieves by deep-UV femtosecond laser ablation

A growing demand for complex light manipulation and miniaturization of optics necessitates advanced optical elements, operating on light diffraction phenomena, capable not only of reshaping the intensity distribution but also integrating many optical functions in a compact, durable device. The prevailing fabrication methods for these elements often involve multi-step lithographic processes. In contrast, direct laser ablation offers a single-step, cost-effective, and maskless alternative. However, using solid-state laser systems’ fundamental wavelength (in the IR range) for ablation lacks the precise depth control required for multi-level diffractive optical element fabrication. In this paper, we present the first experimental proof that femtosecond direct laser ablation in the UV spectral range is a reliable method for fabricating diffractive optical elements. We demonstrate the high-quality production of compact photon sieve focusing elements with the shortest focal length ever reported at 9 mm. Furthermore, we report an efficiency of 3.3%, which, to our knowledge, is the highest for elements with such a small focal length and not far from the theoretical efficiency limit of 4.46% (considering perfect cylindrical ablated pits). Moreover, our fabricated elements focus light to a 2.3% smaller focal spot if compared to the refractive lens with the same parameters. This fabrication method shows great promise for advanced applications that require precise depth control in wide band gap materials, such as the fused quartz used in this study.

Feather keratin in Pavo cristatus: A tentative structure

Abstract Background F-keratin forms an evolutionary conserved nanocomposite which allows birds to fly. Structural models for F-keratin are all based on the pioneering X-ray diffraction studies on seagull F-keratin, first published in 1932, confirmed for other species and refined over the years. There is, however, no experimental proof because native F-keratin does not form a perfect molecular crystal as required for structure determination. Methods Peacock’s tail feathers were systematically re-investigated by taking diffraction patterns at different rotation angles. Using the recently developed AlphaFold algorithm, a collection of 3D models of arbitrarily truncated and multiplied Pavo cristatus F-keratin sequences was created. The shape, dimensions, density and interfacial exposure of functionally relevant amino acid side chains of the calculated 3D building blocks were used as the initial selection criteria for filamentous F-keratin precursors. Full reproducibility of in silico folding and agreement with previous results from mechanical testing, biochemical analyses and SAXS experiments was mandatory for suggesting the tentative structure for the novel F-keratin repeating unit. Results The filament of the F-keratin polymer is an alternating arrangement of two units called "N-block" and "C-block": Four strands AA 1–52 form a disulfide-stabilized twisted parallelepiped, with 89° internal rotation within eight levels of β-sandwiches. Four strands AA 81–100 form a two-level “β-sandwich” in which aromatic residues provide resilience, like vertebral discs in a spinal column. The pitch of an N+C-block octamer is 10 nm. Solidification may involve "C-blocks" to temporarily mold into "C-wedges" of 18° tilt, which align F-keratin into laterally amorphous fiber-reinforced composites of 9.5 nm axial periodicity. This experimentally significant distance corresponds to the fully stretched AA 53–80 matrix segment. The deformed “spinal column” unwinds under compression when F-keratin filaments perfectly align horizontally into stacked sheets in the solid state. Conclusions At present, the tentative structure presented here is without alternatives.

4hJCHOCH Spin Coupling in a Lewisx Trisaccharide as Evidence of Inter-Residue C-H···O Hydrogen Bonding in Aqueous Solution.

Prior studies of the solution conformation of the Lewisx (Lex) trisaccharide, αFuc-(1→3)[βGal-(1→4)]-βGlcNAc, suggest that nonclassical inter-residue C-H···O hydrogen bonding in aqueous solution contributes to the stabilization of its 3D structure and affects its biological properties. Experimental evidence for this hydrogen bond in aqueous solution has been reported in the form of a 4hJCHOCH NMR spin-coupling constant between C5'Fuc and H1″Gal measured by 2D NMR methods in unlabeled samples. A methyl glycoside of Lex (MeβLex) was prepared containing selective 13C-labeling at C5'Fuc, and the H1″Gal signal was examined in high-field 1H NMR spectra for evidence of splitting or line-broadening caused by the 13C at C5'Fuc. High-resolution 1H NMR spectra obtained at high field and at different temperatures using different FID processing parameters showed no resolved splitting of the H1″Gal signal or evidence of line-broadening. Spectral simulation showed that this splitting and/or line-broadening would be observable if the reported J-value (∼1.1 Hz) is correct. DFT calculations on MeβLex and a carbon analog (O5″Gal replaced by a CH2 group) gave very small and nearly identical calculated 4hJC5',H1″ values, suggesting that the coupling is essentially zero. DFT calculations also showed that an alternate inter-residue 3hJH5',H1″ is small. Based on NMR analyses and DFT calculations, we found that 4hJC5',H1″ in MeβLex has an upper limit of ∼0.4 Hz and that the value could be lower, possibly zero, calling into question its value as experimental proof of persistent nonclassical hydrogen bonding in aqueous solutions of MeβLex and related structures.

Development of crystal optics for X-ray multi-projection imaging for synchrotron and XFEL sources.

X-ray multi-projection imaging (XMPI) is an emerging experimental technique for the acquisition of rotation-free, time-resolved, volumetric information on stochastic processes. The technique is developed for high-brilliance light-source facilities, aiming to address known limitations of state-of-the-art imaging methods in the acquisition of 4D sample information, linked to their need for sample rotation. XMPI relies on a beam-splitting scheme, that illuminates a sample from multiple, angularly spaced viewpoints, and employs fast, indirect, X-ray imaging detectors for the collection of the data. This approach enables studies of previously inaccessible phenomena of industrial and societal relevance such as fractures in solids, propagation of shock waves, laser-based 3D printing, or even fast processes in the biological domain. In this work, we discuss in detail the beam-splitting scheme of XMPI. More specifically, we explore the relevant properties of X-ray splitter optics for their use in XMPI schemes, both at synchrotron insertion devices and XFEL facilities. Furthermore, we describe two distinct XMPI schemes, designed to faciliate large samples and complex sample environments. Finally, we present experimental proof of the feasibility of MHz-rate XMPI at the European XFEL. This detailed overview aims to state the challenges and the potential of XMPI and act as a stepping stone for future development of the technique.

Feasibility of Surface Nuclear Magnetic Resonance With Absurdly Long Excitation Pulses

AbstractThe common understanding in surface nuclear magnetic resonance (NMR) is that the excitation pulse should be kept much shorter than the NMR relaxation times for an effective excitation. We present analytic, numerical, and experimental evidence demonstrating that this need not be so, and surface NMR signals can be retrieved even for absurdly long excitation pulses. We solve the Bloch equations in the limit of infinitely long excitation and use this result to demonstrate that a measurable magnetization can be obtained with long excitation pulses. We perform numerical simulations of the Bloch equations incorporating effects of relaxation‐during‐pulse, and our results suggest that long excitation pulses can be used to increase the depth of investigation, but that the spatial resolution of long pulse excitation is low. Data collected in Kompedal, Denmark using up to 3 s long excitation pulses provide experimental proof for the feasibility of long pulse surface NMR.

Demonstrating Brownian motion and estimating Avogadro’s number using simple tools: a practical guide for students

Abstract Brownian motion provides crucial observational evidence for the kinetic molecular theory by demonstrating the random perpetual movement of small particles. This phenomenon underscores the existence and behaviour of atoms and molecules, fundamentally supporting our current understanding of molecular kinetic theory. Remarkably, in 1905 Albert Einstein was able to predict this motion exactly purely from a theoretical point of view and in 1908 Jean Perrin provided experimental proof. This provided experimental proof of the existence of atoms and molecules. This paper outlines a method to demonstrate and record Brownian motion using a drop of homogenised low fat milk, a microscope and a mobile phone. The captured video files can be analysed with Physics Tracker software, allowing for the estimation of Avogadro’s number.

Coherent combining of broadband pulses after free space optical parametric amplification.

In this study, we present the experimental proof of concept of the polarization-based filled-aperture coherent combination of two distinct broadband (sub-20 fs transform limited pulse duration at around 795 nm central wavelength) optical parametric chirped pulse amplification systems in free space. An average combination efficiency of 90% is demonstrated.

Visible-wavelength and monostatic coherent transceiver with independent second harmonic generation on transmitted and local lights using commercially available lithium niobate phase modulator for fundamental wavelength

We propose what we believe to be a new monostatic coherent transceiver at visible wavelength using a commercially available lithium niobate (LiNbO3) phase modulator (LNPM), which is capable of high-speed, wide-bandwidth, and multi-functional operation. The proposed coherent transceiver needs successful heterodyne detection with independent second harmonic generation (SHG) on transmitted and local lights. Experimental proof of the above-mentioned heterodyne detection is shown. The proof of concept for the application to continuous-waves coherent Doppler lidar (CW-CDL) is shown in both free-space and underwater sensing. Preliminary experiment regarding high-speed and wide-bandwidth modulation is additionally shown.

Nature-based cool pavements for urban overheating mitigation: Experimental proof of concept

Global warming is leading to more frequent and intense heat waves, transforming urban areas into inhospitable environments, particularly during the summer, due to the exacerbation of the urban overheating effect. Outdoor pavements, which account for 20–40 % of urban surfaces, play a crucial role in this phenomenon due to their dark colour and low albedo, resulting in high surface temperatures and the accumulation of thermal energy released into the environment. This study introduces a nature-based solution to mitigate the impact of urban overheating by cooling outdoor pavements using water from existing fountains or ponds in cities. The water functions as a coolant, significantly reducing the surface temperature of the pavement by up to 25 °C compared to dry samples exposed to the sun. The innovative aspect of this concept lies in the fact that the pavements do not exhibit capillarity, thereby achieving sensible cooling without evaporation and subsequent water consumption. The concept's impact is examined by considering pavements of varying thicknesses and albedos. In the conducted experiments, water-cooled pavements 100 % eliminated the risk of overheating compared to air temperature. This strategy offers an effective and sustainable approach to counteract the adverse effects of urban overheating in cities.

Deep subwavelength topological edge state in a hyperbolic medium.

Topological photonics offers the opportunity to control light propagation in a way that is robust from fabrication disorders and imperfections. However, experimental demonstrations have remained on the order of the vacuum wavelength. Theoretical proposals have shown topological edge states that can propagate robustly while embracing deep subwavelength confinement that defies diffraction limits. Here we show the experimental proof of these deep subwavelength topological edge states by implementing periodic modulation of hyperbolic phonon polaritons within a van der Waals heterostructure composed of isotopically pure hexagonal boron nitride flakes on patterned gold films. The topological edge state is confined in a subdiffraction volume of 0.021 µm3, which is four orders of magnitude smaller than the free-space excitation wavelength volume used to probe the system, while maintaining the resonance quality factor above 100. This finding can be directly extended to and hybridized with other van der Waals materials to broadened operational frequency ranges, streamline integration of diverse polaritonic materials, and compatibility with electronic and excitonic systems.

Experimental Proof of the Effect of Induced Optical Coalescence of Bubston Clusters at Water Breakdown Induced by Picosecond and Nanosecond Laser Pulses

Experimental Proof of the Effect of Induced Optical Coalescence of Bubston Clusters at Water Breakdown Induced by Picosecond and Nanosecond Laser Pulses

Multislit gamma camera for external beam radiotherapy assistance: Experimental proof of concept

The orthogonal computed tomography (OrthoCT) concept, based on orthogonal ray imaging, is a low-dose imaging technique currently under investigation to potentially aid in external-beam radiation therapy treatments. This technique involves detecting radiation scattered within the patient and emitted at approximately 90° from the direction of the incoming beam. This scattered radiation can be collected by a 1D-detector system with a multisliced collimator positioned perpendicular to the incident beam axis. Such a system holds promise for on-board imaging with the patient positioned and prepared for treatment, as well as for real-time treatment monitoring. In this study, a multi-slice OrthoCT detector prototype was developed and tested under in-beam irradiation. The system utilizes gadolinium orthosilicate scintillator crystals coupled to photomultiplier tubes and a collimator made of lead slices. Experimental measurements were conducted using a heterogeneous phantom made of acrylic with an air cavity inside. The phantom was irradiated with a TrueBeam linac operating at 6 MV in the flattening-filter-free mode. The findings of this study indicate that this innovative imaging technique is capable of providing morphological images of the phantom. This accomplishment is achieved without the need to rotate the X-ray source around the object to be irradiated, demonstrating the feasibility of such a system.

Interstitial dual-mode ultrasound with a 3-mm MR-compatible catheter for image-guided HIFU and directional in-vitro tissue ablations.

Current interstitial techniques of tumor ablation face challenges that ultrasound technologies could meet. The ablation radius and directionality of the ultrasound beam could improve the efficiency and precision. Here, a 9-gauge MR-compatible dual-mode ultrasound catheter prototype was experimentally evaluated for Ultrasound Image-guided High Intensity Focused Ultrasound (USgHIFU) conformal ablations. The prototype consisted of 64 piezocomposite linear array elements and was driven by an open research programmable dual-mode ultrasound platform. After verifying the US-image guidance capabilities of the prototype, the HIFU output performances (dynamic focusing and HIFU intensities) were quantitatively characterized, together with the associated 3D HIFU-induced thermal heating in tissue phantoms (using MR thermometry). Finally, the ability to produce robustly HIFU-induced thermal ablations in in-vitro liver was studied experimentally and compared to numerical modeling. Investigations of several HIFU dynamic focusing allowed overcoming the challenges of miniaturizing the device: mono-focal focusing maximized deep energy deposition, while multi-focal strategies eliminated grating lobes. The linear-array design of the prototype made it possible to produce interstitial ultrasound images of tissue and tumor mimics in situ. Multi-focal pressure fields were generated without grating lobes and transducer surface intensities reached up to Isapa = 14 W·cm-2. Seventeen elementary thermal ablations were performed in vitro. Rotation of the catheter proved the directionality of ablation, sparing non-targeted tissue. This experimental proof of concept demonstrates the feasibility of treating volumes comparable to those of primary solid tumors with a miniaturized USgHIFU catheter whose dimensions are close to those of tools traditionally used in interventional radiology, while offering new functionalities.

Advances in Deep Learning Assisted Drug Discovery Methods: A Self-review

: Artificial Intelligence is a field within computer science that endeavors to replicate the intricate structures and operational mechanisms inherent in the human brain. Machine learning is a subfield of artificial intelligence that focuses on developing models by analyzing training data. Deep learning is a distinct subfield within artificial intelligence, characterized by using models that depict geometric transformations across multiple layers. The deep learning has shown significant promise in various domains, including health and life sciences. In recent times, deep learning has demonstrated successful applications in drug discovery. In this self-review, we present recent methods developed with the aid of deep learning. The objective is to give a brief overview of the present cutting-edge advancements in drug discovery from our group. We have systematically discussed experimental evidence and proof of concept examples for the deep learning-based models developed, such as Deep- BindBC, DeepPep, and DeepBindRG. These developments not only shed light on the existing challenges but also emphasize the achievements and prospects for future drug discovery and development progress.

Genome Mining for Diazo-Synthesis-Related Genes in Streptomyces sp. CS057 Unveiled the Cryptic Biosynthetic Gene Cluster crx for the Novel 3,4-AHBA-Derived Compound Crexazone 2.

Natural products play a crucial role in drug development, addressing the escalating microbial resistance to antibiotics and the treatment of emerging diseases. Progress in genome sequencing techniques, coupled with the development of bioinformatics tools and the exploration of uncharted habitats, has highlighted the biosynthetic potential of actinomycetes. By in silico screening for diazo-related gene genomes from twelve Streptomyces strains isolated from Attini leaf-cutting ants, the new crx biosynthetic gene cluster (BGC) was identified in Streptomyces sp. CS057. This cluster, highly conserved in several Streptomyces strains, contains genes related to diazo group formation and genes for the biosynthesis of 3,4-AHBA. By overexpressing the LuxR-like regulatory gene crxR1, we were able to activate the crx cluster, which encodes the biosynthesis of three 3,4-AHBA-derived compounds that we named crexazones (CRXs). The chemical structure of crexazones (CRXs) was determined by LC-DAD-HRMS-based dereplication and NMR spectroscopic analyses and was found to correspond to two known compounds, 3-acetamido-4-hydroxybenzoic acid (CRX1) and the phenoxazinone texazone (CRX3), and a novel 3,4-AHBA-containing compound herein designated as CRX2. Experimental proof linking the crx BGC to their encoded compounds was achieved by generating mutants in selected crx genes.

Required fatigue strength (RFS) – a simple concept for determining an equivalent stress range indicating the necessary minimum joint quality in contrast to the actual modified equivalent strength (MES) method

This paper treats different fatigue (FAT)-scenarios for determining damage-equivalent stress ranges according to two methods for transforming a stress or load spectrum into a damage-equivalent constant amplitude loading, i.e., the Modified Equivalent Stress (MES) and the Required Fatigue Strength (RFS) concepts. The MES method is suggested by the IIW-recommendations for fatigue design and the RFS method is applied especially in the design of vehicle safety components. The resulting MES- and RFS-ranges are similar, but not equal. The MES-method delivers a damage-equivalent stress range that depends on the selected FAT-value, i.e., the position of the Woehler-curve is decisive. In contrast, the RFS-method results in a damage-equivalent fictitious Woehler-line that indicates the lowest necessary strength quality for a given stress spectrum. The allocation of the modified equivalent stress range to the appertaining bi-linear Woehler-curve does not result in the fatigue life caused by the spectrum. Only in the case of a linear Woehler-curve, the fatigue life is directly obtained. In the case of the RFS-application, the fatigue life is by definition equal to the spectrum length. For durability tests, the modified equivalent stress range (at LS\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${L}_{S}$$\\end{document} cycles) and the associated FAT-Woehler-curve should not be used. However, the Woehler-curve derived by the RFS-method allows experimental durability proofs for any amplitude-cycle combination along it. Furthermore, the required lowest necessary strength also enables the selection of the most cost-effective manufacturing technique and quality. The RFS-Woehler-curve also results in a FAT-value with a defined probability of failure depending on the required safety factor.

Theory of time constant correlation of a porous bed thermal energy storage tank - Experimental and numerical proof of concept

Analytical modeling of energy systems is used to estimate the potential of the system, but several simplifications used lead to progressive deviations from the actual potential. Thermal Energy Storage tanks are most often treated as black boxes, by limiting their characteristics to their energy efficiency and basic capacity only. This paper introduces the theory of a time constant that correlates the basic parameters of a porous bed heat storage tank and allows the charge level of the tank to be determined during the charging stage. The correlation for the time constant has a coefficient that has been fully validated both experimentally and numerically for a wide range of parameters. Coefficient values for different precision test runs have been indicated, and the prediction deviation using the time constant does not exceed a value of 5 % relative to the actual results. The proposed methodology for the analytical model of the tank accurately represents the cyclic operation of the heat storage tank. It has also been shown that the cyclic operation of the heat storage tank fixes the charge level in the range of 0.16–0.79. The methodology presented can be used to modelling and designing energy systems with heat storage.

Implicit bias in large language models: Experimental proof and implications for education

We provide experimental evidence of implicit racial bias in a large language model (specifically ChatGPT 3.5) in the context of an educational task and discuss implications for the use of these tools in educational contexts. Specifically, we presented ChatGPT with identical student writing passages alongside various descriptions of student demographics, including race, socioeconomic status, and school type. Results indicate that when directly prompted to consider race, the model produced higher overall scores than responses to a control prompt, but scores given to student descriptors of Black and White were not significantly different. However, this result belied a subtler form of prejudice that was statistically significant when racial indicators were implied rather than explicitly stated. Additionally, our investigation uncovered subtle sequence effects that suggest the model is more likely to illustrate bias when variables change within a single chat. The evidence indicates that despite the implementation of guardrails by developers, biases are profoundly embedded in ChatGPT, reflective of both the training data and societal biases at large. While overt biases can be addressed to some extent, the more ingrained implicit biases present a greater challenge for the application of these technologies in education. It is critical to develop an understanding of the bias embedded in these models and how this bias presents itself in educational contexts before using LLMs to develop personalized learning tools.