Birefringence Analysis Research Articles

FEM analysis of birefringence, dispersion and nonlinearity of graphene coated photonic crystal fiber

Abstract A novel D-shaped photonic crystal fiber (D-PCF) is proposed to concurrently achieve ultra-high nonlinearity, birefringence, and numerical aperture profile. Also, the model consists of a single core design with a series of air holes that are arranged in a rectangular manner. However, the entire analysis is finished through by COMSOL Multiphysics software with 235430 mesh elements using the finite element method (FEM) for 0.1 μm–1.5 μm wavelength. In fact, the evanescent fields of the structure help to the simulation process and that exhibit the performance profile with an ultra-high birefringence of 0.17, the outstanding high numerical aperture of 0.80 and ultra-high nonlinearity of 7.1 × 1024 W−1Km−1. From the designed model, an outstanding negative dispersion of −6533 ps/(nm.km) has been derived which is highly beneficial for optical communication. Nonetheless, graphene is used as a core material and silica is used in the core-cladding region to compensate for unwanted radiation. Simplicity in geometry makes it more acceptable in the fabrication process. To sum up, the overall performance of the PCF makes it more appropriate in optical propagation of non-telecom and telecom applications.

Combined Raman and polarization sensitive holographic imaging for a multimodal label-free assessment of human sperm function

Raman microspectroscopy (RM) and polarization sensitive digital holographic imaging (PSDHI) are valuable analytical tools in biological and medical research, allowing the detection of both biochemical and morphological variations of the sample without labels or long sample preparation. Here, using this multi-modal approach we analyze in vitro human sperm capacitation and the acrosome reaction induced by heparin. The multimodal microscopy provides morphofunctional information that can assess the sperms ability to respond to capacitation stimuli (sperm function). More precisely, the birefringence analysis in sperm cells can be used as an indicator of its structural normality. Indeed, digital holography applied for polarization imaging allows for revelation of the polarization state of the sample, showing a total birefringence of the sperm head in non-reacted spermatozoa, and a birefringence localized in the post-acrosomal region in reacted spermatozoa. Additionally, RM allows the detection and spectroscopic characterization of protein/lipid delocalization in the plasma and acrosomal membranes that can be used as valuable Raman biomarkers of sperm function. Interestingly, these spectral variations can be correlated with different time phases of the cell capacitation response. Although further experimentation is required, the proposed multimodal approach could represent a potential label-free diagnostic tool for use in reproductive medicine and the diagnosis of infertility.

Design and analysis of high birefringence and nonlinearity with small confinement loss photonic crystal fiber

High birefringence with low confinement loss photonic crystal fiber (PCF) has significant advantages in the field of sensing, dispersion compensation devices, nonlinear applications, and polarization filter. In this report, two different models of PCFs are presented and compared. Both the models contain five air holes rings with combination of circular and elliptical air holes arrangement. Moreover, the elliptical shaped air holes polarization and the third ring air holes rotational angle are varied. To examine different guiding characteristics, finite element method (FEM) with perfectly matched layer (PML) absorbing boundary condition is applied from 1.2 to 1.8 μm wavelength range. High birefringence, low confinement loss, high nonlinearity, and moderate dispersion values are successfully achieved in both the PCFs models. Numeric analysis shows that model-1 gives higher birefringence (2.75 × 10–2) and negative dispersion (–540.67 ps/(nm$km)) at 1.55 μm wavelength. However, model-2 gives more small confinement loss than model-1 at the same wavelength. In addition, the proposed design demonstrates the variation of rotation angle has great impact to enhance guiding properties especially the birefringence.

Evaluation of biological behavior of odontogenic keratocyst and orthokeratinized odontogenic cyst using picrosirius red stain: A clinicopathological retrospective study

Background: Odontogenic keratocyst (OKC) and orthokeratinized odontogenic cyst (OOC) show considerable difference in biological behavior, and the study of the organization of collagen fibers may be helpful in understanding the nature of these variants. Aims: The purpose of this study is to determine the clinicopathological features and to analyze the birefringence of collagen fibers in OKC and OOC using picrosirius red stain to delineate its exact role in biological behavior. Materials and Methods: Clinical data were obtained from the case records of 71 patients, and for the analysis of birefringence, paraffin-embedded blocks of 10 cases each of OKC and OOC were retrieved from the archives of our department during the period of 2010–2018. Tissue sections were obtained and stained with picrosirius red stain to determine the birefringence of collagen fibers in both the variants. Statistical analysis was done by unpaired t-test. Results: Out of 71 cases, 61 were OKC and 10 were OOC. The clinicopathological data revealed that the most common affected age group was third decade with male predilection and the most common site noted was posterior mandible, and considerable difference in birefringence was noted in the collagen fibers of OKC and OOC. Conclusion: The study results analyzing the clinicopathological parameters of OKC and OOC could act as a viable record for the distribution of odontogenic lesions in the sample population. Significant differences in birefringence were demonstrated in OKC and OOC, suggesting that different collagen fibers may exist in the two lesions.

Chronical treatment with sildenafil causes Achilles tendinopathy in rats

AimsThe primary goal was to assess the effects of chronic sildenafil treatment over the Achilles tendons in rats. Main methodsAnimals were divided into two groups, control and sildenafil administration (n = 5). After 60 days, the tendons were subject to biochemical and image analysis to compare tendons between the groups: collagen I and decorin content, polarisation microscopy and birefringence analysis, and tissue zymography. Key findingsThe animals exposed to sildenafil presented a much less organised tendon matrix, with reduced collagen I and non-collagenous protein content and a much higher decorin content. SignificanceThe results observed in the animals can be characterised as tendinopathy, a condition not yet described as a sildenafil side effect.

Birefringent PCF-Based SPR Sensor for a Broad Range of Low Refractive Index Detection

An asymmetrical birefringence photonic crystal fiber based on a surface plasmon resonance (SPR) sensor designed to detect the low analyte refractive indexes is investigated by a novel birefringence analysis method. The results show that the birefringent analysis method can replace the conventional confinement loss method pertaining to the investigation SPR on the asymmetrical structures. The air holes in the sensor are arranged in a square lattice structure and two active plasmonic gold layers are deposited on the inner surface of the left and right channels to enhance the SPR phenomenon. The birefringence sensor shows a broad refractive index detection range from 1 to 1.43 with the maximum wavelength sensitivity of 6300 nm/RIU.

Determination of the size distribution of non-spherical nanoparticles by electric birefringence-based methods

The in situ determination of the size distribution of dispersed non-spherical nanoparticles is an essential characterization tool for the investigation and use of colloidal suspensions. In this work, we test a size characterization method based on the measurement of the transient behaviour of the birefringence induced in the dispersions by pulsed electric fields. The specific shape of such relaxations depends on the distribution of the rotational diffusion coefficient of the suspended particles. We analyse the measured transient birefringence with three approaches: the stretched-exponential, Watson-Jennings, and multi-exponential methods. These are applied to six different types of rod-like and planar particles: PTFE rods, goethite needles, single- and double-walled carbon nanotubes, sodium montmorillonite particles and gibbsite platelets. The results are compared to electron microscopy and dynamic light scattering measurements. The methods here considered provide good or excellent results in all cases, proving that the analysis of the transient birefringence is a powerful tool to obtain complete size distributions of non-spherical particles in suspension.

Texture analysis applied to polarimetric images of healthy in vivo murine skin

The imaging and digital processing of anisotropic optical properties of in vivo skin may be helpful in the assessment of its heterogeneous anatomy and physiological functioning. The interaction between polarized light and this organ provides information about the structural order beneath the epidermal layer. However, penetration depth is limited by optical absorption and scattering that are related to local skin characteristics such as pigment density, connective tissue organization, and cutaneous layer thickness. In this work, in vivo healthy skin of a murine model was analyzed using Mueller imaging polarimetry. A gray-level co-occurrence matrix analysis of diattenuation, birefringence, and depolarization measures in four different skin locations showed texture properties that can be used to distinguish local physiology.

Bioactive glass-ceramic bone repair associated or not with autogenous bone: a study of organic bone matrix organization in a rabbit critical-sized calvarial model.

The aim of the study was to analyze bone matrix (BMX) organization after bone grafting and repair using a new bioactive glass-ceramic (Biosilicate®) associated or not with particulate autogenous bone graft. Thirty rabbits underwent surgical bilateral parietal defects and divided into groups according to the materials used: (C) control-blood clot, (BG) particulate autogenous bone, (BS) bioactive glass-ceramic, and BG + BS. After 7, 14, and 30days post-surgery, a fragment of each specimen was fixed in - 80°C liquid nitrogen for zymographic evaluation, while the remaining was fixed in 10% formalin for histological birefringence analysis. The results of this study demonstrated that matrix organization in experimental groups was significantly improved compared to C considering collagenous organization. Zymographic analysis revealed pro-MMP-2, pro-MMP-9, and active (a)-MMP-2 in all groups, showing gradual decrease of total gelatinolytic activity during the periods. At day 7, BG presented more prominent gelatinolytic activity for pro-MMP-2 and 9 and a-MMP-2, when compared to the other groups. In addition, at day 7, a 53% activation ratio (active form/[active form + latent form]) was evident in C group, 33% in BS group, and 31% in BG group. In general, BS allowed the production of a BMX similar to BG, with organized collagen deposition and MMP-2 and MMP-9 disponibility, permitting satisfactory bone remodeling at the late period. The evaluation of new bone substitute, with favorable biological properties, opens the possibility for its use as a viable and efficient alternative to autologous bone graft.

Photobiomodulation mechanisms in the kinetics of the wound healing process in rats

ObjectivesThe healing process of cutaneous lesions is considered a complex event divided into distinct and overlapping phases, which responds satisfactorily to photobiomodulation (PBM). PBM is indicated as a therapeutic resource capable of assisting tissue repair. The present study aimed to analyze the kinetics of cutaneous wounds healing process after application of the GaAlAs laser for treating wounds on the dorsum of rats. Materials and MethodsThis study was approved by the Animal Ethics Committee of UFSCar. The animals were divided into 2 groups (n = 10); control group (CG) used 0.9% saline solution and the laser group (LG) used GaAlAs, 670 nm continuous pulse, 30 mW power, 14.28 J/cm2 energy density, irradiating 1 point per wound for 30s, totaling 15 consecutive days of treatment. Samples were collected on the 4th, 11th and 16th days for histological analysis of HE, Picrosirius-Red, immunohistochemistry (Collagen1, TNF-α, VEGF). Statistical analyzes used the one-way ANOVA test for intra and inter group evaluations, and the Tukey post-test. Level of significance was set at p < 0.05. ResultsThe histopathological analysis (HE) showed a statistically significant difference for lower values of inflammatory infiltrate in LG versus CG on the 16th day; and for the increase of collagen in the 11th and 16th days of treatment. There was a statistically significant difference in the increase of VEGF on the 11th day for LG; decrease of TNF-α on the 4th and 11th day for LG, and increase of collagen type 1 on the 4th and 16th days for LG. The birefringence analysis of the percentage of collagen fibers presented on the 11th day of treatment revealed a greater quantity and significant statistical difference. Collagen fibers showed improved organization and arrangement on the 11th day for LG. ConclusionOur results show that PBM is effective in helping the kinetics of the cutaneous wound healing process in rats and promotes the necessary stimuli for the satisfactory evolution of healing process, ultimately leading to structurally desirable tissue.

Effective D-shape fiber with air hole assistant design for birefringence analysis

We propose an elliptic core effective D-shaped fiber with air hole assistant for birefringence applications. The proposed birefringent fiber works on the principle of asymmetric core region. The birefringence of the proposed D-shaped fiber has been numerically investigated in detail. The designed fiber has effective mode areas of 16.04 μm2 and 16.06 μm2 for x-and y-polarization modes, respectively, at a wavelength of 1550 nm. Our numerical results reveal a birefringence and confinement loss of 2.25 × 10−4 and 6.66 × 10−3 dB/m respectively at 1550 nm wavelength. The proposed fiber exhibits a dispersion variation of 1.3 ps/km-nm and 1.57 ps/km-nm respectively for x-and y-polarizations over a wavelength band of 200 nm ranging from 1.4 to 1.6 μm. We have also investigated the influence of variation in the fiber parameters on the birefringence and dispersion. Furthermore, we have calculated the fabrication tolerances, the variation of birefringence value is very small by varying the air hole diameters of the fiber. We believe that the reported results have potential importance in the design and development of polarization control devices applicable in fiber-optic sensors.

Effect of different resistance-training protocols on the extracellular matrix of the calcaneal tendon of rats

The calcaneal tendon extracellular matrix (ECM) is composed of collagen, non-collagenous glycoproteins and proteoglycans, and able to adapt to various biomechanical stimuli. The objective of this study was to analyze the response of different resistance-training protocols, such as hypertrophy, strength and resistance, on the organization of the calcaneal tendon after training. Wistar rats were divided into four groups: untrained (UT), resistance training (RT), hypertrophy training (HT), and strength training (ST). The protocol in a vertical climbing platform was performed thrice per week over twelve weeks. For biochemical study, the tendons of each group were minced and analyzed for gelatinases, quantification of non-collagenous proteins, sulfated glycosaminoglycans, and hydroxyproline. For morphological analysis, sections were stained with HE and toluidine blue. Non-stained sections were used for birefringence analysis under polarization microscopy. The highest hydroxyproline concentrations were found in HT (154.8±14.2) and RT (173.6±25.2) compared with UT (122.4±27.0). A higher concentration of non-collagenous proteins was detected in the RT group (14.98mg/g) compared with the other groups. In polarization microscopy, major birefringence was observed in HT and the lowest in ST compared with UT, indicating higher organization of collagen bundles in HT. In analysis for zymography, the presence of latent MMP-9 was more prominent in the ST group and the active MMP-9 more prominent in the HT group. For MMP-2, significant differences in the latent isoform between the HT (184,867±6765) and UT (173,018±9696) groups were found. In sections stained with toluidine blue (TB), higher metachromasia was observed in the tendon’s distal region in HT and RT groups, indicating a greater amount of proteoglycans. We conclude that the different training protocols produced different responses in the ECM. The remarkable presence of MMP-2 and -9 in the hypertrophy training group may be related to the highest organization of collagen bundles and possibly a more efficient remodeling process, observed in that group, as demonstrated by images and measurements of birefringence.

Photonic bandgaps in selectively filled photonic crystal fibers

Simulations of selectively filled photonic crystal fibers using finite elements method were performed. Different patterns of filling were modeled and compared to an empty and fully filled fiber. Dependence of effective refractive indices of guided modes, phase birefringence and confinement losses on guided wavelength was investigated. A comparison of width of photonic bandgaps in different structures was made. Full Text: PDF ReferencesPh. St. J. Russell, "Photonic-Crystal Fibers", J. Lightwave Technol. 24, 4729 (2006) CrossRef Y. Han, S. Tan, M. K. K. Oo, D. Pristinski, S. Sukhishvili, and H. Du, "Towards Full-Length Accumulative Surface-Enhanced Raman Scattering-Active Photonic Crystal Fibers", Adv. Mat. 22, 2647 (2010) CrossRef S. Ertman, A. H. Rodríguez, M. M. Tefelska, M. S. Chychłowski, D. Pysz, R. Buczyński, E. Nowinowski-Kruszelnicki, R. Dąbrowski, and T. R. Woliński, "Index Guiding Photonic Liquid Crystal Fibers for Practical Applications", J. Lightwave Technol. 30, 1208 (2012) CrossRef K. Mileńko, S. Ertman, T. R. Woliński, "Numerical Analysis of the Phase Birefringence of the Photonic Crystal Fibers Selectively Filled with Liquid Crystal", Mol. Cryst. Liq. Cryst. 596, 4 (2014) CrossRef Y. Wang, C. Liao, X. Zhong, Z. Li, Y. Liu, J. Zhou, and K. Yang, "Selective-fluid-filled photonic crystal fibers and applications", Proc. SPIE 8914, 89140J-1 (2013) CrossRef F. Wang, W. Yuan, O. Hansen, and O. Bang, "Selective filling of photonic crystal fibers using focused ion beam milled microchannels", Opt. Express 19, 17585 (2011) CrossRef T. Martynkien, G. Statkiewicz-Barabach, J. Olszewski et al., "Highly birefringent microstructured fibers with enhanced sensitivity to hydrostatic pressure", Opt. Express 18, 15113 (2010) CrossRef B. T. Kuhlmey, R.C. McPhedran, C. M. de Sterke, "Modal cutoff in microstructured optical fibers", Opt. Lett. 27, 1684 (2002) CrossRef

Reflectance-yarn geometry relation of false-twist textured olive hue poly(ethylene terephthalate) mass dyed yarn in visible–near-infrared region

This study was conducted on the visible–near-infrared camouflage properties of olive hue poly(ethylene terephthalate) multifilament mass dyed yarn textured by two texturizing method (simultaneous and conventional). The effect of thermal process and structural changes on the reflectance, mechanical, and crimp properties of these yarns was studied using the DSC, XRD, and birefringence analyses. It was observed that simultaneously textured mass dyed multifilament yarns have higher crimp properties and lower mechanical properties. Furthermore, the effect of yarns’ geometry in the fabric structure on the reflectance properties was investigated using images of fabric structure. The results showed that the reflectance behavior of fabric sample is affected by two major factors, namely structural and geometrical factors; it is clear that the geometrical factor has a significant effect on the reflectance properties.

DNA Binding with Acetate Bis(1,10-phenanthroline)silver(I) Monohydrate in a Solution and Metallization of Formed Structures.

The study of DNA interaction with the acetate bis(1,10-phenanthroline)silver(I) monohydrate in a solution is of interest both for understanding the mechanism of biological activity of silver compound and for forming ordered structures (DNA fibrils) that can be used to solve various problems in the field of nanotechnology. The analysis of changing the DNA conformation (secondary structure, persistent length and volume effects) during the interaction by the methods of UV spectroscopy with the analysis of DNA melting, circular dichroism, viscosity, flow birefringence, AFM (atomic force microscopy) and SEM (scanning electron microscopy) was performed. The formation of two types of complexes was observed. At lower concentration of compound in DNA solution, silver atoms form the coordination bonds with a macromolecule, while the released phenanthroline ligands intercalate between DNA bases. When the concentration of the compound increases, the phenanthroline ligands form an ordered “layer” around the helix. The excess of silver compounds in the DNA solution (with more than five silver atoms per base pair), DNA precipitation is observed with the formation of long fibrils. It was shown that the binding of silver to DNA during the formation of complexes provides further metallization of the resulting structures with the aid of reducing agents; phenanthroline ligands influence the result of such metallization.

Thermal characterization of Bragg gratings in polarization-maintaining optical fibres: analysis of birefringence and regeneration

This paper presents an analysis of birefringence and regeneration of fibre Bragg gratings (FBGs) in two types of polarization-maintaining (PM) optical fibres, bow tie and internal elliptical cladding (IEC), with different diameters. The thermal regeneration of FBGs in PM fibres with different degrees of saturation (weakly, slightly, and strongly saturated) is presented and the influence of the gratings’ saturation degree on the birefringence of PM fibres is shown. The birefringence values obtained for IEC fibres with 80 µm of diameter were for a strongly saturated seed grating of 5.3 × 10−4 and 6.2 × 10−4 refractive index units after the regeneration. The evolution of the fibre birefringence as a function of the temperature is presented and the results show hysteresis and nonlinear dependence of the birefringence on temperature. The thermal stability of regenerated gratings in PM fibres is demonstrated, and a sensitivity coefficient value of 0.0035 dBm min−1 at 900 °C was obtained. The results obtained show the feasibility of optimization of fibre birefringence; this could allow such fibers to be used as temperature sensors and even improve the birefringence after the grating regeneration.

Analysis of Residual Stress and Birefringence in a Transparent Injection Molded Article for Molding Condition

Residual stresses are developed during injection molding process and these cause a warpage and invoke a bire- fringence in a molded article. The levels of residual stresses are dependent of molding conditions, such as melt tem- perature, mold temperature, cooling condition, and packing condition. Among the residual stress measurement methods, the photoelasticity method is simple and convenience to measure compared with other methods. However this method can be utilized only for a transparent product. Birefringence and residual stress have been observed in injection molded polycarbonate (PC), polystyrene (PS), and polymethylmethacrylate (PMMA) specimens according to injection molding conditions. Computer simulation has been performed and compared with experimental observation of birefringence. PS specimen showed the highest birefringence whereas PMMA showed the lowest birefringence among them. Locations close to the gate showed higher residual stress than locations far from the gate. Long cooling time, high injection tem- perature, and long packing time reduced residual stress.

Pressure-Induced Birefringence Analysis of Side-Hole Optic Fiber

Pressure-Induced Birefringence Analysis of Side-Hole Optic Fiber

Development and characterization of chitosan bionanocomposites containing oxidized cellulose nanocrystals

ABSTRACTIn this research, cellulose nanocrystals (CNs) were extracted from corn cobs by 2,2,6,6,‐tetramethylpiperidine‐1‐oxyl radical‐mediated oxidation combined with ultrasonic treatment for the first time. These CNs were then used as a mechanical reinforcement agent and barrier in chitosan‐based bionanocomposite films. Birefringence analyses under crossed polarizers indicated the presence of isolated nanocrystals in suspension, which was later confirmed by TEM analysis. The crystallinity index obtained from X‐ray diffraction was 92.4%. The incorporation of these nanoparticles into a filmogenic matrix of chitosan made it possible to obtain bionanocomposite films with improved properties. The water‐vapor permeability was reduced by 70%, whereas the tensile strength and Young's modulus increased by up to 136 and 224% respectively. The developed films were applied as interleaving of sliced cheese, and the efficiency was assessed by investigation of adhesion between the surfaces and by comparing its properties with two commercial interleaving products (polyethylene (PE), and Greasepel paper (GP)). Concluding, the developed films showed a substantial potential to be exploited as an interleaving film, owing to its excellent mechanical properties, permeability, hydrophobicity, and low surface adhesion compared to pure chitosan, PE, and GP films. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43033.

Quality characteristics, structural changes, and storage stability of semi-dried noodles induced by moderate dehydration: Understanding the quality changes in semi-dried noodles

Based on the critical water content (for noodle deterioration) concluded previously, high-temperature–short-time (HTST; 105–135°C) and medium-temperature–long-time (MTLT; 45–75°C) dehydrations were introduced in this study to produce semi-dried noodles. The effects of HTST and MTLT on the quality parameters of semi-dried noodles, as well as noodle structure, storage stability, and changes in starch and protein components were thoroughly investigated. Differential scanning calorimeter (DSC) and birefringent analysis presented few starch gelatinization (approximately 30%) in HTST dehydrated noodles. Scanning electron microscopy (SEM) images showed more compact noodle surface, with uniform pores in the cross section, probably due to enhanced protein–starch combination after HTST dehydration. Meanwhile, HTST induced protein polymerizations in semi-dried noodles, mainly by –SH–S–S interchange, and resulted in significantly (P<0.05) reduced cooking loss. Furthermore, HTST noodles showed higher microbial and color stability. Shelf-life of dehydrated samples at 120°C was extended to 5days from 1day of the control.