Absence Of Birefringence Research Articles

Design, development and characterization of the Apremilast and Indomethacin coamorphous system

Our main aim in the present investigation, preparation of a drug-drug coamorphous system (CAM) of Apremilast (APR) and Indomethacin (INDO) to improve physiochemical properties, solubility and stability. Various solid-state characterization techniques were used to characterize the prepared APR-INDO CAM system. Single Tg in DSC, hallow pattern in PXRD, and absence of birefringence in PLM indicate the formation of the CAM system between APR and INDO. The molecular level interaction in the CAM system was studied using ATR-FTIR and 1H NMR. The molecular modeling-based analysis was performed to understand intermolecular interactions in the CAM system. Solubility and dissolution studies were carried out to investigate the benefits of the CAM system over its crystalline and amorphous forms of APR and INDO. The CAM system was stable for five months under 40 ± 2 °C and 75 ± 5 % RH. In the permeation study, CAM system had an 8.19-fold higher flux for APR and a 5.83-fold higher flux for INDO compared to crystalline APR and INDO, respectively. The APR-INDO CAM system showed anti-psoriatic and anti-melanogenic activity from the molecular docking results. As a result, we determined that the developed CAM-based supersaturated system has improved physicochemical properties and physical stability.

Geometric phase for twisted light.

Polarization vectors of light traveling in a coiled optical fiber rotate around its propagating axis even in the absence of birefringence. This rotation was usually explained due to the Pancharatnam-Berry phase of spin-1 photons. Here, we use a purely geometric method to understand this rotation. We show that similar geometric rotations also exist for twisted light carrying orbital angular momentum (OAM). The corresponding geometric phase can be applied in photonic OAM-state-based quantum computation and quantum sensing.

Birefringence properties of human immotile spermatozoa and ICSI outcome

Research questionIn sperm samples with complete asthenozoospermia, pregnancies are achieved by intracytoplasmic sperm injection (ICSI), but this condition has a negative impact on fertilization and embryo development owing to the difficulty of identifying viable cells for oocyte injection. Is the selection of sperm cells with head birefringence properties under polarizing light a successful strategy to identify viable spermatozoa? DesignThis study included 192 ICSI cycles with complete asthenozoospermia (83 ejaculated and 109 testicular samples) performed under polarized light. Two types of sperm head birefringence were distinguished: partial (presumably reacted spermatozoa) and total (presumably intact acrosome). In some sperm cells, no birefringence was present. The main outcome of the study was the cumulative live birth rate (cLBR) per ICSI cycle. ResultsSeventy-three deliveries resulted with 38.0% cLBR per ICSI cycle. The injection of birefringent spermatozoa led to significantly higher rates of fertilization, embryo development and implantation compared with the absence of birefringence (P < 0.001). Similarly, the resulting cLBR were 53.6% and 9.0%, respectively (P < 0.001). Spermatozoa with partial head birefringence yielded significantly higher fertilization and embryo utilization rates compared with total birefringence. The cLBR showed the same trend (62.7% and 46.7%, respectively, P = 0.048). Multiple logistic regression analysis showed the pattern of partial birefringence to be strongly associated with live birth rate. ConclusionsImmotile sperm cells with birefringence properties under polarized light have higher chances of inducing fertilization and embryo development compared with non-birefringent cells. In addition, a pattern of partial birefringence, associated with a reacted acrosome, is the strongest predictive factor for live birth delivery, both in ejaculated and testicular samples.

Reflection of Light by a Hyperbolic Metamaterial Layer in a Case of Propagation of Special Inhomogeneous Waves in It

The boundary problem of reflection of electromagnetic waves by a hyperbolic metamaterial layer under conditions of total reflection from the boundary with this layer in the absence of birefringence has been solved. In this case, so-called “special inhomogeneous electromagnetic waves” may propagate in the layer. Analytical expressions are obtained for the vector amplitudes of the waves reflected by the layer and transmitted through it and for the special inhomogeneous electromagnetic waves propagating in this layer. These expressions allows calculating the energy characteristics of reflected and transmitted light for an optically uniaxial metamaterial.

Отражение света слоем гиперболического метаматериала в случае распространения в нем особых неоднородных волн

AbstractThe boundary problem of reflection of electromagnetic waves by a hyperbolic metamaterial layer under conditions of total reflection from the boundary with this layer in the absence of birefringence has been solved. In this case, so-called “special inhomogeneous electromagnetic waves” may propagate in the layer. Analytical expressions are obtained for the vector amplitudes of the waves reflected by the layer and transmitted through it and for the special inhomogeneous electromagnetic waves propagating in this layer. These expressions allows calculating the energy characteristics of reflected and transmitted light for an optically uniaxial metamaterial.

High sensitivity and specificity of the Pediatric Vision Scanner in detecting strabismus and amblyopia in preschool children

The Pediatric Vision Scanner (PVS) directly detects strabismus and amblyopia by analyzing binocular scans for the presence or absence of birefringence, which is characteristic of steady, bifoveal fixation. In a preliminary study (AAPOS 2012), the PVS demonstrated 98% sensitivity and 88% specificity. Here we report the sensitivity and specificity for a large cohort, confidence intervals, and analyses of screening errors. 250 children (2-6y) were enrolled; 103 controls and 147 with strabismus and/or amblyopia. In addition to the PVS, children were tested with the SureSight autorefractor and the Randot Preschool Stereoacuity test (RPST). Each test yielded a recommendation of “pass” or “refer.” A comprehensive pediatric ophthalmic examination served as the gold-standard. The PVS correctly identified 144 of 147 children with strabismus and/or amblyopia; sensitivity = 98% (95%CI: 95-100%). The PVS correctly identified 89 of 102 control children; specificity = 87% (95% CI, 79%-96%). The SureSight misclassified 81 children, failing to detect 49 children with strabismus and/or amblyopia and over-referring 18 children with astigmatism. The RPST misclassified 51 children, including similar numbers of affected and control children. Misclassifications were not consistent across tests. Using Bayesian analysis to estimate the performance of each test in a preschool screening setting (assuming a prevalence of 4%), accuracies of 88%, 69%, and 77% were predicted for the PVS, SureSight, and RPST tests, respectively. The PVS identifies children with strabismus and/or amblyopia with high sensitivity, outperforming the SureSight and the RPST. Preschool vision screening may be more efficient with a device that directly detects strabismus and/or amblyopia.

Preparation, characterization, sterility validation, and in vitro cell toxicity studies of microemulsions possessing potential parenteral applications

Context: Water-in-oil microemulsions (w/o ME) are ideal for parenteral drug delivery. However, no such formulations have been tested for biocompatibility in in vitro cell cultures. Furthermore, sterilization of w/o MEs is a challenging process that has not been previously developed and validated.Purpose: To formulate pharmaceutically relevant water-in-oil (w/o) microemulsion’s systems suitable for use as a parenteral formulation.Methods: w/o MEs were prepared using dioctyl sodium sulfosuccinate (DOSS), ethyl oleate (EO), and water. Formulations were characterized using polarized light microscopy, electrical conductivity, rheology, and dynamic light scattering. An aseptic filtration method for sterilization was developed using membrane filtration. The biocompatibility of selected MEs were evaluated in NIH3T3 cell cultures. Dissolution studies were performed on microemulsions containing methylene blue to evaluate the drug release profile.Results: The maximum amount of water incorporated in the formulations was 14% w/w. DOSS/EO/water microemulsions exhibited Newtonian flow. Particle sizes for these MEs were less than 30 nm in size. Formulations filtered aseptically were free of bacteria when gram-stained and visualized under a microscope. All MEs showed no toxicity to NIH 3T3 cells.Discussion: The absence of birefringence and low conductivity values indicated that the formulations were w/o microemulsions. The filtration method of sterilization was validated by the absence of microbial growth on blood agar plates over a 14-day period. In vitro dye release studies demonstrate sustained release of the model drug over a 72-h time period.Conclusion: Characteristics delineated in this study demonstrate the potential for these formulations to be used as parenteral preparations.

Hybrid plasmon/dielectric waveguide for integrated silicon-on-insulator optical elements

VLSI compatible optical waveguides on silicon are currently of particular interest in order to integrate optical elements onto silicon chips, and for possible replacements of electrical cross-chip/inter-core interconnects. Here we present simulation and experimental verification of a hybrid plasmon/dielectric, single-mode, single-polarization waveguide for silicon-on-insulator wafers. Its fabrication is compatible with VLSI processing techniques, and it possesses desirable properties such as the absence of birefringence and low sensitivity to surface roughness and metallic losses. The waveguide structure naturally forms an MOS capacitor, possibly useful for active device integration. Simulations predict very long propagation lengths of millimeter scale with micron scale confinement, or sub-micron scale confinement with propagation lengths still in excess of 100 microns. The waveguide may be tuned continuously between these states using standard VLSI processing. Extremely long propagation lengths have been simulated: one configuration presented here has a simulated propagation length of 34 cm.

Structural changes and alkaline solubility of wood cellulose fibers after enzymatic peeling treatment

Two dissolving sulphite wood pulps were treated by an enzymatic peeling protocol and the changes in terms of structure and alkaline solubility were analyzed. The enzymatic treatment leads to a fast and large decrease of degree of polymerization and of crystallinity, showing that the enzymes do not simply act on the fiber surface. The swelling and dissolution behaviour of the treated samples showed that the enzyme mixture used has two effects at short peeling times (i) a digestion of the primary wall which is seen by the near absence of ballooning and (ii) a destructive action on the inside of the fiber which is seen by the large decrease in the degree of polymerization. At long peeling times, the external walls are totally digested and the fiber structure is totally destroyed, as seen by the absence of birefringence. The alkaline solubility of the different treated samples was investigated in a NaOH 8%–water solution. As expected from thermodynamic considerations, there is a direct correlation between the solubility and the degree of polymerization. However, aside thermodynamics, the removal of the external walls and the macrostructural destructuration of the fibers are key factors in the improvement of the dissolution of wood cellulose fibers. At constant intrinsic viscosities of the cellulose materials, the alkaline solubility is almost two times higher when the external walls are removed. The macrostructural destructuration of fibers by enzymes allows a high degree of polymerization to be preserved while keeping a good alkaline solubility.

Cerenkov radiation in a Lorentz-violating and birefringent vacuum

We calculate the emission spectrum for vacuum Cerenkov radiation in Lorentz-violating extensions of electrodynamics. We develop an approach that works equally well in the presence or the absence of birefringence. In addition to confirming earlier work, we present the first calculation relevant to Cerenkov radiation in the presence of a birefringent photon k{sub F} term, calculating the lower-energy part of the spectrum for that case.

Optically isotropic mesophase in comb-shaped copolymers with side mesogenic groups

Two series of comb-shaped copolymers poly(4-(4-cyanobiphenyl-4′-yloxy)butyl acrylate)-co-(4-(6-acryloyloxyhexyl-1-oxy)isophthalic acid)) and poly(4-(6-acryloyloxyhexyl-1-oxy)benzoic acid)-co-(acrylic acid)) have been prepared by free-radical copolymerization, and their phase diagrams have been constructed. Formation of the optically isotropic phase characterized by the absence of birefringence and high optical activity has been demonstrated for a number of copolymers. At the same time, the DSC curves of these compounds show a well-defined phase transition with the heat of melting equal to 2–5 J/g. Specific features of hydrogen bonding in the copolymers have been studied by IR spectroscopy. It has been speculated that there is correlation between microphase separation between hydrophobic and hydrophilic units in the copolymers and formation of the optically isotropic mesophase.

Lorentz violation and superpartner masses

We consider Lorentz violation in supersymmetric extensions of the standard model. We perform a spurion analysis to show that, in the simplest natural constructions, the resulting supersymmetry-breaking masses are tiny. In the process, we argue that one of the strongest bounds on Lorentz violation in the photon Lagrangian, which comes from the absence of birefringence from distant astrophysical sources, does not apply when Lorentz violation is parametrized by a single vector.

Characterizing of tissue microstructure with single-detector polarization-sensitive optical coherence tomography

Assessing tissue birefringence with imaging modality polarization-sensitive optical coherence tomography (PS-OCT) could improve the characterization of in vivo tissue pathology. Among the birefringent components, collagen may provide invaluable clinical information because of its alteration in disorders ranging from myocardial infarction to arthritis. But the features required of clinical imaging modality in these areas usually include the ability to assess the parameter of interest rapidly and without extensive data analysis, the characteristics that single-detector PS-OCT demonstrates. But beyond detecting organized collagen, which has been previously demonstrated and confirmed with the appropriate histological techniques, additional information can potentially be gained with PS-OCT, including collagen type, form versus intrinsic birefringence, the collagen angle, and the presence of multiple birefringence materials. In part I, we apply the simple but powerful fast-Fourier transform (FFT) to both PS-OCT mathematical modeling and in vitro bovine meniscus for improved PS-OCT data analysis. The FFT analysis yields, in a rapid, straightforward, and easily interpreted manner, information on the presence of multiple birefringent materials, distinguishing the true anatomical structure from patterns in image resulting from alterations in the polarization state and identifying the tissue/phantom optical axes. Therefore the use of the FFT analysis of PS-OCT data provides information on tissue composition beyond identifying the presence of organized collagen in real time and directly from the image without extensive mathematical manipulation or data analysis. In part II, Helistat phantoms (collagen type I) are analyzed with the ultimate goal of improved tissue characterization. This study, along with the data in part I, advance the insights gained from PS-OCT images beyond simply determining the presence or absence of birefringence.

Characterization of freestanding polymer films for application in 351-nm, high-peak-power laser systems

Perfluorinated pellicles are screened for thickness uniformity, absence of birefringence, photolytic stability under prolonged UV irradia- tion, and survival strength under pulsed (0.5-ns) high-peak-power laser irradiation. Results prove them to be extraordinarily robust against laser damage, photolytically stable, and better in transmitted wavefront quality than can be measured by state-of-the-art interferometry. © 1998 Society of Photo-Optical Instrumentation Engineers. (S0091-3286(98)04102-6)

Modes of a thermoelastically disturbed resonator

A theoretical analysis is reported of an optical resonator in the form of a circular cylinder with fixed flat reflecting ends subjected to uniform heating. The modes of such a thermoelastically perturbed resonator are calculated in the first order of the perturbation theory using a small parameter describing the anisotropy of thermooptic perturbations. Explicit expressions are obtained (in terms of the Laguerre polynomials) for the perturbed wave functions, particularly for the distorted TEM00 mode. It is shown that the induced birefringence partly lifts the degeneracy of the eigenfrequency spectrum, which—in the absence of birefringence—is analogous to the spectrum of a hollow resonator in the form of a circular ellipsoid.

The nature of reaction wood. IX. Anomalous cases of reaction anatomy

The reaction anatomy of 14 species of Acacia, Lagunaria pattersoni, and the woody monocotyledons Dracaena fragrans and D. marginata was examined with light, polarizing, and ultraviolet microscopes. Notable features of the reaction wood fibres of Acacia spp. were: the absence of birefringence in the sublayers of the "gelatinous" layer at all stages of their deposition; the absence of radial striations in the gelatinous layer; the frequency of occurrence of fibres lacking protoplasts and with convoluted gelatinous layers at some intermediate stage of development; the relatively wide separation of stages of gelatinous layer formation in passing from cambium towards pith; and the poor adherence of the gelatinous layer to previously formed cell wall layers. It was concluded that the forces bringing about gelatinous layer deposition were either weaker or slower to develop, or both, than in species such as Tristania conferta. Possible reasons for this are discussed. Deposition of starch grains in reaction wood fibres occurred in all Acacia spp, towards the end of the growing season. A gelatinous layer did not occur in reaction wood fibres of Lagunaria pattersoni. These differed from normal fibres only in the thinness of their walls and their relatively large cross-sectional area. Examination of the wall structure of phloem fibres indicated that changes in microfibril orientation towards a more axial position which occurred in layer S2 of primary phloem fibres were accelerated on the upper sides of bent stems. The significance of this feature, and of possible tensions developed in the outer cortex and epidermis on the upper sides of bent stems because of accelerated phloem and xylem development, are discussed in relation to mechanisms whereby such stems may recover to a vertical position. The number of vascular bundles and the wall thickness and extent of lignification of the fibres of the bundle sheaths, were increased on the upper sides of horizontally grown stems of Dracaena spp. The radial width of the cortex and the cross-sectional area of cortical cells were less than on the lower sides of the stems.