Light Diffraction Research Articles

Antibiofilm and cytotoxic potential of extracellular biosynthesized gold nanoparticles using actinobacteria Amycolatopsis sp. KMN

This study intends to biosynthesize gold nanoparticles (AuNPs) using Amycolatopsis sp. KMN and to investigate its potential antibiofilm, cytotoxic and antioxidant activities. The physicochemical characterization of biosynthesize AuNPs was identified by UV-Visible, energy-dispersive X-ray, and Fourier transform infrared spectroscopy, as well as high-resolution transmission electron microscopy, X-ray diffraction, zeta potential, and dynamic light scattering methods. Crystal violet assay and scanning electron microscopy showed that the AuNPs with a particle size of 44.4 nm have a strong antibiofilm activity (at 750 µg/ml concentration) against bacteria strains viz Staphylococcus aureus ATCC 29213, Escherichia coli ATCC 25922, and Pseudomonas aeruginosa ATCC 27853. The result also demonstrated strong cytotoxic activity against two cell lines, MCF-7 and HT-29. The MTT test result displayed that over a period of 48 hr, the IC50 of AuNPs was 600 and 300 µg/ml for MCF-7 and HT-29 cell lines, respectively. The IC50 of AuNPs against DPPH was 46.87 µg/ml. This is the first report that examines Amycolatopsis sp. strain KMN-mediated synthesis of AuNPs is rapid and in situ with antibiofilm and cytotoxicity activities. Moreover, it has the potential for an effective antibiofilm and cytotoxic activity that could be used in future therapeutic applications.

LDI-MS performance of gold nanostars as an inorganic matrix for low molecular weight analytes

Anisotropy at the nanoscale fascinates researchers in various areas of science and technology. Well-known applications of anisotropic nanoparticles include biosensors and catalysis. However, utilization of gold nanostars in analytical chemistry is limited to surface enhanced Raman spectroscopy. LDI-MS assisted with gold nanostars has not been addressed for low molecular weight compounds. Herein, we report LDI-MS performance of phospholipids at nanomolar concentrations with application of gold nanostars for the first time. Intense signals of molecular ions were detected as metal adduct ions with relatively low fragmentation and signals of interferences in low-mass region. Nanostars were characterized with utilization of electron microscopic, X-Ray powder diffraction and dynamic light scattering techniques. The results showed that gold nanostars can serve as a bright perspective for new inorganic matrices in LDI-MS of low molecular weight compounds.

Development of an educational device, based on Arduino, to facilitate the understanding of light diffraction

The Arduino board and its communication with several sensors are becoming more and more popular in the physical science community. They offer inspiring possibilities for learning different physical concepts. In this article, we focused on creating a very practical educational system for experimenting with diffraction of laser light and graphically visualizing the distribution of light intensity in space, which is impossible to perform it with the devices available in the educational laboratories of physics. The main elements of this configuration are the Arduino UNO microcontroller board, the BH1750 sensor and the NEMA17 motor and its A4990 driver. The results’ graph is displayed in real time on the computer using the Data Streamer add-in. We see that the abbreviated curve corresponds well to the theory. In addition, feedback from the participants in the test activity of the device showed that they were satisfied with its operation and its contribution to the understanding of diffraction. Therefore, we believe that the device presented can play a very important role in the diffraction phenomenon learning because of its high precision and reliability in the measurements.

Consensus Receptor-Binding Domain-Targeted Aptamer Selection and Designing of a Photonic Crystal-Decorated Aptasensor for SARS-CoV-2.

The frequent emergence of variants of concern (VOC) of SARS-CoV-2 necessitates a sensitive and all-inclusive detection platform that remains viable despite the virus mutations. In this context, we targeted the receptor-binding domain (RBD) of glycoprotein (S-protein) of all VOC and constructed a consensus RBD (cRBD) based on the conserved amino acids. Then, we selected a high-affinity ssDNA novel aptamer specific for the cRBD by an in silico approach. The selected aptamer is utilized to fabricate a photonic crystal (PC)-decorated aptasensor (APC-sensor), which consists of polystyrene nanoparticles polymerized within a polyacrylamide hydrogel. cRBD-responsive ssDNA aptamers are crosslinked in the hydrogel network, which selectively bind to the cRBD and SARS-CoV-2 in saliva samples. The binding response can be visually monitored by swelling of the hydrogel and color generation by diffraction of light from PCs and can be quantified by the diffraction ring diameter or a spectrometer. The sensor delivers a LOD of 12.7 ± 0.55 ng mL–1 for the cRBD and 3 ± 18.8 cells mL–1 for SARS-CoV-2 in saliva samples, with a rapid response of 5 min. The sensor can be stored and regenerated without loss of activity. It can be utilized as a point-of-care testing (POCT) for SARS-CoV-2 diagnosis.

Generation of Complex Tunable Multispectral Signatures with Reconfigurable Protein-Based, Plasmonic-Photonic Crystal Hybrid Nanostructures.

Structurally colored materials, which rely on the interaction between visible light and nanostructures, produce brilliant color displays through fine control of light interference, diffraction, scattering, or absorption. Rationally combining different color-selective functions into a single form offers a powerful strategy to create programmable optical functions which are otherwise difficult, if not impossible to obtain. By leveraging structural protein templates, specifically silk fibroin, nanostructured materials that combine plasmonic and photonic crystal paradigms are shown here. This confluence of function enables directional, tunable, and multiple co-located optical responses derived from the interplay between surface plasmon resonance and photonic bandgap effects. Several demonstrations are shown with programmable coloration at varying viewing sides, angle, and by solvent infiltration, opening avenues for smart displays and multi-mode information encoding applications.

First steps into coherent object classification using convolutional deep diffractive neural networks

Abstract As artificial intelligence and deep learning becomes more important, new approaches for photonic neural computing arise. We investigate the concept of deep diffractive neural networks. First proposed in 2018, deep diffractive neural network operate passively, using coherent images and diffractive optics to do image-to-image regression and object classification. In this article we shortly review current approaches, give a brief introduction into the mathematical description of such diffractive networks using the Angular Spectrum method and show the first results of our own developments of convolutional diffractive networks with an experimental accuracy of approximately 84 %. The objective of this article is to give an introduction into the field of optical computing with neural networks using diffraction and free-space propagation of light.

Cascadable all-optical NAND gates using diffractive networks

Owing to its potential advantages such as scalability, low latency and power efficiency, optical computing has seen rapid advances over the last decades. Here, we present the design and analysis of cascadable all-optical NAND gates using diffractive neural networks. We encoded the logical values at the input and output planes of a diffractive NAND gate using the relative optical power of two spatially-separated apertures. Based on this architecture, we numerically optimized the design of a diffractive neural network composed of 4 passive layers to all-optically perform NAND operation using diffraction of light, and cascaded these diffractive NAND gates to perform complex logical functions by successively feeding the output of one diffractive NAND gate into another. We numerically demonstrated the cascadability of our diffractive NAND gates by using identical diffractive designs to all-optically perform AND and OR operations, which can be formulated as mathrm{AND}left({I}_{1}, {I}_{2}right)=mathrm{NAND}left(mathrm{NAND}left({I}_{1}, {I}_{2}right), mathrm{NAND}left({I}_{1},{I}_{2}right)right) and mathrm{OR}left({I}_{1}, {I}_{2}right)=mathrm{NAND}left(mathrm{NAND}left({I}_{1}, {I}_{1}right), mathrm{NAND}left({I}_{2},{I}_{2}right)right), respectively. We also designed an all-optical half-adder that takes two logical values as input and returns their sum and the carry using cascaded diffractive NAND gates. Cascadable all-optical NAND gates composed of spatially-engineered passive diffractive layers can serve optical computing platforms.

An introduction to lithography methods and providing a practical method for its optimization

In the first part of the present article, the important and main methods of photolithography are reviewed and discussed. Then we introduce the ways to improve the images created on the photoresist, which is the main material of lithography. Lithography with high-energy particle and soft lithography are then described. In the second part, the contact-photolithography method and its improvement process, which we use in our laboratory, are introduced and described in detail. We used this method for lithography to make diffraction optical elements on a glass substrate, doped by silver nanoparticles, using a helium ion beam. Light diffraction from the created lithography masks prevents access to very small images. To reduce the diffraction influence on the quality of the produced elements, we adapted and optimized the contact-lithography method for our project. Our solution, presented in this article, is practical and available for other researchers in Iran

Development of Five-Step Diagnostic Test on Light Wave Concepts to Analyze Students’ Understanding Map on The Concepts

During the Physics learning processes, students often have difficulty in understanding the concepts so that misconceptions occur. This is what was found in the Light Wave concepts when the Authors did the pre-research at one high school in Nganjuk. For example in Light Diffraction, students assumed that light diffraction be able to bending when it passes through all slit size, does not produce interference, and new waves. The truth is, diffraction in Light Wave occurs when light bends through a small slit and is characterized by interference and a new wave pattern. The misconceptions that occur in the Light Wave have the potential to hinder students' understanding of the following concepts, so they must be detected immediately. This article intends to report the results of writing the five-step conception diagnostic test on the Light Wave concepts, examine its feasibility, and then use it to map students' understanding concepts, as well as to identify the most dominant internal factors that lead students' misconceptions. Based on the feasibility test results, ten valid and reliable questions were selected so they can be used to test students' conceptions. The details are: the internal validity 96% (very valid), the external content validity consists of Correct Fake and Incorrect Fake scores are 3.3% and 4.5% (<10%) respectively, the construct external validity (rxy)=0.416>rtable=0.2638, and the reliability (r11)=0.796 (very reliable). Of the 19 students that were mapped using this feasible diagnostic test, 61.05% of them experienced a lack of knowledge.

The intensity of diffractive light for the ultrasonic grating for oblique incidence in water

The intensity of diffractive light for the ultrasonic grating for oblique incidence in water

Diffraction properties of light with transverse orbital angular momentum

The spatiotemporal optical vortex (STOV) is unique, owing to its phase singularity in the space–time domain, and it can carry transverse orbital angular momentum (OAM). Diffraction is a fundamental wave phenomenon that is well known for conventional light; however, studies on the diffraction of light with transverse OAM are limited. Furthermore, methods that enable the fast detection of STOVs are lacking. Here, we theoretically and experimentally study the diffraction behaviors of STOVs, which are different from those of conventional light. The diffraction patterns of STOV pulses that are diffracted by a grating exhibit multilobe structures with a gap number that corresponds to the topological charge. The diffraction rules of STOVs are also revealed. An approach for the fast detection of STOVs is provided using their special diffraction properties. This method has potential applications in fields that require fast STOV recognition, such as STOV-based optical communications.

Investigating the Effect of Taheri Consciousness Fields on the Behavior of the Laser Light in Passing through an Aperture and Observing the Heisenberg Uncertainty Principle

Investigating the behavior of light in the vicinity of an aperture and observingHeisenberg’s uncertainty is a classic experiment in optics. Studies of TaheriConsciousness Fields (TCFs)include the study of different fields of physicsin the systems under study. By applying a TCF to the system under thestudy, changes in the behavior of the system as a function of the Field areobserved. The present study was performed with two aims: (a) Investigationof the effect of TCFs on the pattern of the laser light diffraction through anaperture (in Fraunhofer diffraction patterns). (b) Investigation of the effect ofTCFs on the behavior of light and observation of Heisenberg’s uncertaintyprinciple in these conditions. Applying TCFs to the laser light-independentof the set-up experiment did not affect the light behavior. On the other hand,applying TCFs to the set-up of the light-passing test through an aperturehas a significant effect on the light behavior in passing through the aperture.In such a way, the uncertainty and diffraction width in the state of treatmentwith TCFs is reduced compared to the control. This behavior is interpreted asreducing the effect of the observer in optics studies, where the aperture hasbeen considered equivalent to an observer. In other words, this change in thelight behavior as a result of applying the TCFs can be considered a processof direct observation (without intermediaries) of the system under the studyusing the TCF. This study indicates the high potential of the effects of TCFson the known laws of physics, as an innovative tool in science.

Reconfigurable liquid crystal diffraction grating based on flexoelectric effect

Reconfigurable optical diffraction grating is of great importance for monochromator, spectrometer, optical fiber telecommunication, laser protection, antenna and more. We report a liquid crystal diffraction grating based on flexoelectric effect. When no voltage is applied, the liquid crystal is unidirectionally aligned and does not diffract light. When a DC voltage is applied, the liquid crystal is switched to a 1-dimensional periodic structure due to flexoelectric interaction and becomes diffracting. The periodicity and refractive index undulation of the periodic structure are determined by the elastic energy, due to the spatial variation of the liquid crystal director, and flexoelectric interaction energy. The diffraction angle and efficiency can be controlled by the applied voltage. The liquid crystal diffraction grating has the advantages of low driving voltage, high diffraction efficiency and independency of the polarization of incident light.

Photonic crystal L3 cavity laser fabricated using maskless digital photolithography

Abstract Projection photolithography using an extreme-ultraviolet light source is the core technology that has enabled patterning on the scale of a few nanometers that is required for modern electronic chips. However, this high-end system is neither affordable nor needed for photonics where critical feature sizes are of 100s of nanometers (or of submicron). Although electron-beam lithography can provide a means for photonic device fabrication, it suffers from extremely low throughput. Therefore, a lithographic technique for submicron pattern generation at high throughput and low cost is in high demand. This group recently showed that maskless digital photolithography (MDPL), a convenient and versatile photolithographic technique that requires no photomask, could potentially address this demand by demonstrating photonic crystal (PhC) patterns with submicron periodicity and associated PhC band-edge lasers. In this paper, we report the fabrication of a PhC L3 cavity laser, which contains irregular air holes in terms of their positions and sizes, using the MDPL technique. Successful generation of such an aperiodic and nontrivial submicron pattern requires thorough understanding and scrupulous manipulation on light diffraction. Our achievements should provide the concrete foundation upon which compact, versatile, convenient, speedy, and economical lithographic tools for arbitrary submicron pattern generation can be developed.

Redefinition of De-Broglie Wavelength Associated with Material Particle

The objective of the work is to reveal the Association of special theory of relativity with De-Broglie wavelength of a particle. It shows that wave nature of a particle is always associated with it’s relativistic properties. The phenomena of interference, diffraction and polarization of light can only be explained on the basis of wave theory of light. These phenomena show that light possesses wave nature. However, certain phenomena like photoelectric effect, Compton effect and discrete emission and absorption of radiation can only be explained on the basis of quantum theory. According to this theory , light propagates in a small packets or quanta and behave like corpuscles or particle. This shows that light possesses particle nature. thus, we can say that light possesses dual nature. The matter also possesses the same dual nature. In order to have wave nature, the particle must satisfy the equation Where m denotes the mass of particle when it is moving with certain velocity. h=6.62×10-34 is the plank’s constant. C is the velocity of light in free space. This shows that wavelength of a material Particle depends on mass. When mathematical operation is done on above equation, it give complete quantitative properties about the wave nature of a particle.

Biomimetic Synthesis of Silver Nanoparticles Using Ethyl Acetate Extract of Urtica diocia Leaves; Characterizations and Emerging Antimicrobial Activity.

The current work reports the biosynthesis of silver nanoparticles (AgNPs) using the antimicrobial activities of ethyl acetate extract of Urtica diocia (UD) leaves as a reducing and capping agent. The synthesized UD-AgNPs were characterized using UV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and dynamic light scattering (DLS). The UD-AgNPs were evaluated against Gram-positive and Gram-negative bacteria, and their size, shape, and distribution were recorded. The average size of an NP was 19.401 nm. The zone of inhibition (ZOI) for 75 µL of UD-AgNPs against Pseudomonas aeruginosa (P. aeruginosa) was 21 ± 0.4 mm more than that of the control drug Ciprofloxacin (16 ± 10 mm). The minimum inhibitory concentration (MIC) was the lowest against Escherichia coli (E. coli) (36 ± 3 µg/mL) and Staphylococcus epidermidis (S. epidermidis) (38 ± 3 µg/mL). Moreover, the minimum bactericidal concentration (MBC) was the lowest against E. coli (75 ± 00 µg/mL) and Enterococcus faecalis (E. faecalis (83 ± 16 µg/mL). Thus, the UD-AgNPs synthesized using the ethyl acetate extract of UD can be used as a new antimicrobial drug.

Exploring Fresnel diffraction at a straight edge with a neural network

We describe a research project carried out with a group of undergraduate physics students and aimed at exploring the use of a neural network to study a classical problem in wave optics whose analytical solution is well known: the diffraction of light by the straight edge of an opaque semi-infinite screen. Through this exposure to machine learning, the students were able to appreciate the basic steps involved in a machine-learning process.

Anisotropy of elastic and photoelastic properties of lithium niobate crystals

The elastic and photoelastic constants of lithium niobate crystals and the attenuation coefficients of acoustic waves at room temperature have been determined by the Bragg diffraction of light by sound. The components of the photoelasticity tensor were determined by the modified Dixon method. The obtained values of the constants were used to determine the anisotropy of the effective elastic and photoelastic constants with a change in the direction of propagation of acoustic waves in the (100) symmetry plane, for different directions of the wave vector and polarization of light relative to the sound wave vector. It is shown that, for certain geometries of the Bragg light diffraction, there is a correlation between the orientation dependences of the effective elastic and photoelastic constants in the investigated plane. The results of the study can be used to analyze the anisotropy of the photoelastic properties of lithium niobate crystals and determine the diffraction geometry with the highest efficiency of Bragg light diffraction.

Attenuation of acoustic waves and Grüneisen tensor in lithium fluoride crystals

The anisotropy of acoustic attenuation in lithium fluoride crystals in the range of 0.4–1.6 GHz was studied by the method of Bragg light diffraction on acoustic waves. The obtained values of the velocity and attenuation coefficient of acoustic waves were used to determine all independent real and imaginary elastic constants. Based on the Akhiezer attenuation mechanism, the anisotropy of acoustic attenuation was determined for the propagation of longitudinal and transverse waves in the (001) and (110) planes. All directions along which pure longitudinal and transverse acoustic waves propagate are found. To describe the anisotropy of acoustic attenuation, the Grüneisen acoustic tensor is used for the first time, the components of which have been determined from the values of the attenuation coefficient of acoustic waves along the crystallographic axes [100], [110], and [111]. It is shown that the orientational dependence of the effective Grüneisen constant, defined in terms of the components of this tensor, describes well the anisotropy of the attenuation of acoustic waves in the studied frequency range. The proposed approach can be used to all cubic crystals in which the main attenuation mechanism is the phonon–phonon Akhiezer mechanism.

Low‐diffraction transparent micro light‐emitting diode displays with optimized pixel structure

AbstractTransparent displays suffer from background image blur due to light diffraction when passing through periodic pixel structures. A simple, reference‐image free and semi‐analytical model based on diffraction theory and human eye's angular resolution is proposed to quantitatively evaluate the diffraction effect of transparent displays. Several factors including object distance, resolution and aperture ratio are analyzed with our model to establish guidelines for minimizing the diffraction effect in transparent displays. By optimizing the pixel structures within a 2 × 2‐pixel size region, the relative diffraction intensity is reduced by 42% at the 50% aperture ratio regardless of pixel density, which is valuable for achieving diffraction‐less high resolution and low aperture ratio transparent displays with current fabrication technologies.