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An optical sensor that recognizes various blood constituent types is demonstrated in this work and is based on a pentagonal-shaped cladding photonic crystal fiber (PCF) model with a decagonal core. The terahertz frequency, which spans from 1.2 to 3 THz, has been examined with the goal of improving relative sensitivity with minimal confinement loss. COMSOL Multiphysics software is used to analyze the sensor’s sensing and guiding properties through an implementation of the finite element method (FEM) technique. Regarding the chosen analytes, comprising red blood cells (RBCs), hemoglobin (HB), white blood cells (WBCs), plasma, and water, notable relative sensitivity responses of 97.26%, 96.52%, 95.62%, 95.08%, and 93.84% are attained at a frequency of 2.2 THz. In order the same analytes and THz frequency in y-polarization mode, small confinement loss (CL) of 2.92 × 10−11 dB/m and effective material loss (EML) of 0.0052 cm−1 are also acquired respectively. All of these typical values for the optical characteristics show the biosensor’s potential because they assure higher sensitivity for detecting blood components while minimizing confinement and material loss. [ABSTRACT FROM AUTHOR]

A hybrid photonic crystal fiber (PCF) rectangular-cored wrapping example has been presented for utilization in liquid (petrochemical) detecting purposes. Enhancing relative sensitivity while minimizing confinement loss has been the aim of the THz frequency range of 1.2 – 3.4 THz examination. At 2.2 THz, the suggested sensor exhibits an RS of 91.76% for x-polarization and 91.11% RS for y-polarization. In addition, for x-polarization, the PCF has an EA of 4.00 × 10−08 m2, CL of 3.50 × 10−10 dB/m, spot size of 1.54 × 10−04 μm, and a very small EML of 0.0127 cm−1. For y-polarization, the effective area is 3.02 × 10−08 m2, the CL is 1.94 × 10−10 dB/m, the spot size is 1.547 × 10−04 μm and a very small EML of 0.0252 cm−1. To investigate the overall outcome, full three-dimensional (3D) simulations are performed using COMSOL Multiphysics 5.6 software. Since the device’s rectangular shape core yields comparable findings in each of the polarization of x and y modes. so, our team examined the x,y in each of polarization modes in this work for petrol. The proposed sensor structure is simply constructed using standard manufacturing procedures. The proposed fiber might be considered a key component of practical applications of petrol adulteration measures. [ABSTRACT FROM AUTHOR]

The article presents an illegal drug detector that utilizes photonic crystal fiber (PCF). The fiber structure of the H-PCF comprises a dodecagonal core and circular air gaps in cladding areas. We have analyzed the designed terahertz (THz) frequency range utilizing the Finite Element Method (FEM) and the COMSOL Multiphysics application. The revised design has a high sensitivity in detecting amphetamine (n = 1.518) and cocaine (n = 1.5022) at a frequency of 3 THz, via detection rates of 99.43% and 99.20%, correspondingly. Furthermore, the suggested fiber, which operates at a frequency of 3 THz, has a relatively tiny confinement loss of 4.93×10-08 dB/m and 6.16×10-09 dB/m and a minimal effective material loss of construction of 0.0032 cm-1. In conclusion, it may be stated that drug misuse not only leads to immediate repercussions but also has severe and enduring impacts on human health, potentially resulting in fatality. Hence, it is imperative to accurately and effectively detect illicit substances. H-PCF architecture we offered is well-suited to detect illegal drugs. Doi: 10.28991/ESJ-2024-08-06-020 Full Text: PDF

Skin cancer is a disorder marked by inappropriate skin cell proliferation, which is frequently brought on by UV radiation exposure from tanning booths or the sun. It can present as melanoma, squamous cell carcinoma, or basal cell carcinoma, with varying levels of malignancy and available therapies. Our newly developed photonic crystal fiber (PCF) has exceptional efficacy in the identification of skin cancer. The proposed US model has a heptagonal core and a clad surface with a heptagonal pattern. The PCF analyzer that has just been released shows a maximum relative sensitivity (RS) of 95.35% as well 94.29% for the basal (cancer) alongside basal (normal), respectively. For the aforementioned cells, we also looked at the confinement loss (CL) of 1.74 × 10–14 dB/m, 5.98 × 10–13 dB/m, plus the effective material loss (EML) of 0.0077 cm−1, 0.0088 cm−1. Rapid identification in skin cancer allows for improved results, tailored treatment, and prompt intervention. Early detection of cancer makes milder medications available, which lessens the need for aggressive treatment. Moreover, increasing the treatment of patients and simplifying the continual sickness monitoring process. Accurate evaluation also helps with research into developments that enhance global recognition as well as treatment options. The new PCF, with its exceptional detecting capacity, may have been instrumental in the prompt discovery of such harmful organisms. In summary, there are a lot of opportunities in the medical field. [ABSTRACT FROM AUTHOR]

In today's medical research, breast cancer is a severe problem, so it is imperative to develop a reliable and efficient approach for identifying cancerous breast cells. PCF, with its exceptional sense-making abilities, simplifies and distinguishes that procedure. The research presents a unique structural hybrid PCF for detecting breast cancer cells using sensors based on PCF that are specifically built for the terahertz-frequency range. The improvement in sensor sensitivity and specificity in identifying cancer cells at these frequencies is a notable progress compared to conventional approaches, which could potentially result in earlier and more precise diagnosis. In our analysis, we discovered the most common malignancies in breast cancer. We investigate the features of the cancerous cell detector using the COMSOL-Multiphysics 5.6 software. This PCF detector achieves a Confinement Loss of 4.75 × 10−12 and 3.42 × 10−13 dB/m for Type-1 and Type-2 cancer cells, respectively, at 1.2 THz, as well as about 99.946% and 99.969% relative sensitivity. This sensor ensures the highest level of sensitivity for the identification of cancerous breast cells. This sensor's physical architecture is quite straightforward, making it simple to build using current manufacturing techniques. Therefore, it seems that this sensor will pave a new path for identifying and treating cancerous cells. [ABSTRACT FROM AUTHOR]

In order to rapidly identify various species of cancer cells in the tissues of person, a unique diamond shaped hollow-core photonic crystal fiber (PCF)-formed by optical waveform is developed and computationally studied. In this investigation, we found the most prevalent cancers, such as HeLa-derived cervical carcinoma. Since normal and cancer cells differ in their refractive indices (RIs), other significant optical properties can be assessed using this information. With the use of the finite element method, a computational tool for solving simultaneous equations, the defining characteristics the suggested cancer cell sensor are examined using COMSOL-Multiphysics software. Additionally, strict mesh parts are used to preserve the utmost level of modeling realism. At 2.4 THz, the PCF detector attains a Relative Sensitivity of around 97.51% and 96.29%, Confinement Loss of 6.1 × 10 −09db/m and 4.39 × 10−07db/m with respect to cervical carcinoma cell and cervical normal cell. The straightforward PCF structure provides a wide chance of application using the continuing fabrication technique, based on these conventional values of performance indices. This biosensor utilizes the distinctive refractive characteristics of cancer cells, providing a highly accurate and dependable approach for the early identification of cervical cancer. This has the potential to significantly transform the process of cervical cancer screening. The novel method boosts the ability to detect and identify certain conditions, leading to increased diagnostic capabilities for early treatment and better results for patients. [ABSTRACT FROM AUTHOR]

This model introduced an innovative hollow-core optical waveguide with an octagonal core, specifically designed for rapid detection of various food oil contaminations is founded on the principles of Photonic Crystal Fiber (PCF). By analyzing the refractive index (RI) variations between pure and contaminated oil, we evaluate other essential optical parameters. The characteristics inherent to the suggested food oil sensor are examined using COMSOL Multiphysics v6.1, employing the Finite Element Method (FEM). Highly precise mesh components are included to provide optimal simulation accuracy. The outcomes from the suggested sensor model demonstrate exceptionally strong relative sensitivity of 98.52 % for castor oil, 98.46 % for sunflower oil, 98.41 % for mustard oil, 98.32 % for olive oil, and 98.03 % for coconut oil, all measured at 2 THz. Additionally, the simulation shows a very low confinement loss of 2.37 × 10−12 cm-1, a numerical aperture of 0.242, effective area of 1.1459 × 10–7 m², and effective material loss of 0.0038 cm-1 for castor oil under optimal structural circumstances. The straightforward design of the PCF in the sensor indicates that it can be implemented with ease, given these standard performance indicators. Therefore, it is anticipated that this sensor will open improved avenues for detection and identification of several distinct food oil contaminations. It can be produced using standard fabrication processes.

In this article, an advanced-level type of Photonic Crystal Fiber (PCF) sensor, having a flower shape core with a unique hexagonal cladding, is proposed. Performance for detecting is evaluated in various animal's milk, such as camel, cow, and buffalo milk, with the suggested PCF sensor. The maximum Relative Sensitivities (RS) of the PCF sensor are 88.2 %, 88.5 %, and 88.8 % for detecting camel milk, cow milk, and buffalo milk, respectively. Moreover, it has a negligible Confinement Loss (CL) of 2.04018402 × 10−14 dB/m and Total Loss (TL) of 2.1520000 × 10−01 dB/m and Effective Material Loss (EML) of 0.21520 cm−1. Since Milk is as great source of nutrients such as Calcium, Vitamin D, Vitamin B12, Phosphorus and Protein. The nutrient composition of different animals' milks and their respective quantities are determined by set values at the beginning and differ among the types of milk. As all of them hold the same tone, it becomes challenging to identify them. Our suggested PCF sensor comes with its remarkable detection capacity to identify them. Therefore, the use of suggested PCF sensor will be helpful for both the industry and consumers. For the industry, it aids in ensuring the quality and composition of animal milk. For consumers, it means they can trust that the milk they purchase has been accurately tested and verified for its nutrient content and safety. With the implementation of the PCF sensor, the industry can better ensure the quality and authenticity of animal milk, reducing the risk of fraud and helping consumers make more informed choices about the milk they consume. This contributes to better assurance of proper nutrient intake.

Cyanide is very poisonous and raises environmental problems because of its industrial application and potential as a terrorist weapon. Given CN's toxicity and possible hazard to people, an effective and adaptive detection approach is needed. This specification suggests using a PCF to build a terahertz Hexagonal Core and Curved rectangular air holes sensor to detect NaCN and KCN. The recently created PCF analysis, which was promptly delivered, reveals an RS concentration of 99.62 % for NaCN and a maximum concentration of KCN is 99.08 %. In addition, we analyzed the Confinement Loss (CL) at a value of 5.88 × 10−09 dB/m and 2.07 × 10−05 dB/m, as well as EML at values of 0.0020 cm−1 and 0.0026 cm−1, accordingly, about these hazardous substances. The designed detector can identify NaCN and KCN at low concentrations even with small RI shifts due to its high sensitivity. Real-time NaCN and KCN detection and monitoring through nerve reflexes is essential for life-threatening conditions. It can selectively work in NaCN and KCN, ensuring accurate detection even in complex chemical compositions. Additionally, its tiny size allows for emergency use.

Based on the Richards–Wolf vector diffraction theory, the strong focusing properties of a 4Pi focusing system under the illumination of the azimuthally polarized Laguerre–Gaussian vortex beam, which is modulated by the diffracted optical elements (DOE), are investigated numerically. We mainly study the influence trend of three parameters, which are the ratio (β ), the numerical aperture ( NA ) of the objective lens and the fourth ring parameter of the DOE, on the focal field in the 4Pi focusing system. The results show that three kinds of focusing patterns (the class optical needle, the flattop optical field and the dark channel) can be obtained according to the influence trend of the three parameters on the focal field. And three focal patterns can be converted by changing three parameters. The conversion between these special focal field patterns has potential application value in the optical micro-control field. [ABSTRACT FROM AUTHOR]

Ethanol and Benzene are two compounds constitute two different chemicals with unique properties and compositions. The adopted material describes a state-of-the-art Photonic Crystal Fiber (PCF) containing an unusual hexagon covering an unparalleled web-like core. A greater estimated performance for our PCF monitor is the limit utilization of the above variables, benzene, and ethanol as dangerous chemicals. The newly developed PCF analysis, which was immediately presented out, exposes a most RS, specifically 95.21% as well as a 94.67% maximum benzene plus ethanol. Additionally, we examined Confinement Loss (CL) about 4.674 × 10−3 dB/m, 1.378 × 10−2 dB/m, plus Effective Material Loss (EML) about 0.0078 cm-1, 0.0083 cm−1 related to these harmful chemicals. For to their intense responsiveness, designed detector simplifies identifying benzene as well as ethanol at the trace level if even slight shifts in the RI are detected. Nervous reactions allow swiftly tracking the level of ethanol and benzene in, almost, real-time, which is critical for immediate measures when in a life-threatening situation. They can be targeted very particularly to attract only to ethanol and benzene, so, detection, even in the existence of quite complex chemical records, is precise. Additionally, due to its smallness, it can be applied in emergencies. [ABSTRACT FROM AUTHOR]

Cyanide is very poisonous and raises environmental problems because of its industrial application and potential as a terrorist weapon. Given CN's toxicity and possible hazard to people, an effective and adaptive detection approach is needed. This specification suggests using a PCF to build a terahertz Hexagonal Core and Curved rectangular air holes sensor to detect NaCN and KCN. The recently created PCF analysis, which was promptly delivered, reveals an RS concentration of 99.62 % for NaCN and a maximum concentration of KCN is 99.08 %. In addition, we analyzed the Confinement Loss (CL) at a value of 5.88 × 10 -09  dB/m and 2.07 × 10 -05  dB/m, as well as EML at values of 0.0020 cm -1 and 0.0026 cm -1 , accordingly, about these hazardous substances. The designed detector can identify NaCN and KCN at low concentrations even with small RI shifts due to its high sensitivity. Real-time NaCN and KCN detection and monitoring through nerve reflexes is essential for life-threatening conditions. It can selectively work in NaCN and KCN, ensuring accurate detection even in complex chemical compositions. Additionally, its tiny size allows for emergency use., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

Hollow core photonic crystal fiber is suggested and analyzed in this article for the identification of different blood components present in human blood. In order to visualize the fiber and investigate the performance of that sensor based on COMSOL simulation software, the suggested fiber is numerically analyze in terahertz frequency spectrum from 1.5 to 3 THz to obtain higher relative sensitivity (RS) and NA as well as lower absorption loss and confinement loss (CL) for better sensing applications. The reported hollow core fiber provides better interaction of light and the analytes, so that extremely high RS is achieved at a particular geometric condition. Furthermore, extremely low CL and effective material loss (EML) with high numerical aperture (NA) can be achieved from the suggested sensor which paves the way to apply the fiber in numerous biomedical applications. [ABSTRACT FROM AUTHOR]

This work is to investigate the instrumentation implementing issues of back focal plane (BFP)-typed apertometer. Firstly, we introduce a general instrument architecture of the BFP-typed apertometer, including the hardware (optics and mechanics) of the system, operation procedures of control and measurement system, and also the digital image processing algorithm/software. Secondly, we are the first to discuss the gradual rising effect of total-internal-reflection (TIR) phenomenon, the criteria on how to “exactly” locate the reference ring on BFP images, and the corresponding accuracies. As a significantly important complement, we further discuss three important issues: 1) the influence of Goos–Hänchen shift on numerical aperture (NA) measurement; 2) comparison of one-dimension and two-dimension identification algorithms; and 3) comparison of center locating using Fourier correlation analysis (FCA) and Hough transformation (HT) algorithms. [ABSTRACT FROM AUTHOR]

A solid immersion objective is generally composed of a truncated solid ball and a commercial objective lens. It features higher numerical aperture (NA) than oil-immersion objectives and thus shows capabilities in some applications requiring higher NA or spatial resolutions. Different from commercial products of oil-immersion objectives and their pre labeled NA values, solid immersion objective is generally home-designed/developed, and the theoretical NA is taken as its practical value, which is not suggested. So far, there has been no proper and commercial apparatus to measure this NA value especially for bare solid immersion objectives. In this work, we propose an extremely simple but very practical approach for the measurement, which inherits the concept of Fourier optics but offers some specific features. Furthermore, we specifically propose an algorithm of multipoint reference to achieve high accuracy of NA value. Detailed comparisons between the proposed algorithm and the previous algorithm of single-point reference are elaborated. An experimental prototype of apertometer for solid immersion objective is built up to verify the proposed approach and algorithm. To the best of the authors’ knowledge, this is the simplest, cheapest, and most practical approach and apparatus for the NA measurement of bare solid immersion objective. [ABSTRACT FROM AUTHOR]

We present an endlessly single-mode, bend-insensitive and highly birefringent photonic crystal fibre (PCF) for efficient wave transmission in the terahertz (THz) spectrum. To facilitate flat dispersion and high birefringence, a diamond-shaped porous core is introduced inside the Zeonex (background material)-based hexagonal porous cladding. Moreover, the dense geometrical arrangement of the regular hexagonal lattice in the cladding region holds maximum usable optical power inside the porous core. The major geometrical parameter of the proposed PCF such as core porosity has been optimized to improve the optical guiding parameters. The numerically investigated outcomes have shown an ultrahigh birefringence and numerical aperture of 0.0888 and 0.57, respectively. Apart from this, very low bending and material losses of 3.01 × 10 - 20 cm−1 and 0.01451 cm−1 with flattened dispersion variation of ± 0.2463 ps/THz/cm have been achieved over the broad THz band (i.e. 0.8–1.3 THz). Additionally, our proposed PCF sustains endlessly single-mode operation with a very high core power fraction of 75.28%. With all these promising results, the proposed PCF would be a potential candidate for polarization preserving as well as for efficient broadband transmission applications in the THz regime. [ABSTRACT FROM AUTHOR]

We theoretically simulate second-harmonic generation (SHG) in collagen under linearly polarized focused laser beam. With this model, the effects of numerical aperture (NA) and refractive index dispersion on SHG emission have been investigated. Dispersion properties of collagen are significant under incident wavelength in the visible range. Our results show that the efficient SHG is obtained by controlling the NA, and the higher NA is a necessity when the dispersion effect is considered. Our theoretical simulation results provide useful clues for experimental study of microscopic SHG emission in collagen excited by focused beam. [ABSTRACT FROM AUTHOR]

Abstract: Performing fluorescence microscopy and electron microscopy on the same sample allows fluorescent signals to be used to identify and locate features of interest for subsequent imaging by electron microscopy. To carry out such correlative microscopy on vitrified samples appropriate for structural cryo-electron microscopy it is necessary to perform fluorescence microscopy at liquid-nitrogen temperatures. Here we describe an adaptation of a cryo-light microscopy stage to permit use of high-numerical aperture objectives. This allows high-sensitivity and high-resolution fluorescence microscopy of vitrified samples. We describe and apply a correlative cryo-fluorescence and cryo-electron microscopy workflow together with a fiducial bead-based image correlation procedure. This procedure allows us to locate fluorescent bacteriophages in cryo-electron microscopy images with an accuracy on the order of 50nm, based on their fluorescent signal. It will allow the user to precisely and unambiguously identify and locate objects and events for subsequent high-resolution structural study, based on fluorescent signals. [Copyright &y& Elsevier]

Abstract: Correlative light and electron microscopy (CLEM) is an emerging technique which combines functional information provided by fluorescence microscopy (FM) with the high-resolution structural information of electron microscopy (EM). So far, correlative cryo microscopy of frozen-hydrated samples has not reached better than micrometre range accuracy. Here, a method is presented that enables the correlation between fluorescently tagged proteins and electron cryo tomography (cryoET) data with nanometre range precision. Specifically, thin areas of vitrified whole cells are examined by correlative fluorescence cryo microscopy (cryoFM) and cryoET. Novel aspects of the presented cryoCLEM workflow not only include the implementation of two independent electron dense fluorescent markers to improve the precision of the alignment, but also the ability of obtaining an estimate of the correlation accuracy for each individual object of interest. The correlative workflow from plunge-freezing to cryoET is detailed step-by-step for the example of locating fluorescence-labelled adenovirus particles trafficking inside a cell. [Copyright &y& Elsevier]

Abstract: Notch4 is a divergent member of the Notch family of receptors that is primarily expressed in the vasculature. Its expression implies an important role for Notch4 in the vasculature; however, mice homozygous for the Notch4d1 knockout allele are viable. Since little is known about the role of Notch4 in the vasculature and how it functions, we further investigated Notch4 in mice and in cultured cells. We found that the Notch4d1 allele is not null as it expresses a truncated transcript encoding most of the NOTCH4 extracellular domain. In cultured cells, NOTCH4 did not signal in response to ligand. Moreover, NOTCH4 inhibited signalling from the NOTCH1 receptor. This is the first report of cis-inhibition of signalling by another Notch receptor. The NOTCH4 extracellular domain also inhibits NOTCH1 signalling when expressed in cis, raising the possibility that reported Notch4 phenotypes may not be due to loss of NOTCH4 function. To better address the role of NOTCH4 in vivo, we generated a Notch4 null mouse in which the entire coding region was deleted. Notch4 null mice exhibited slightly delayed vessel growth in the retina, consistent with our novel finding that NOTCH4 protein is expressed in the newly formed vasculature. These findings indicate a role of NOTCH4 in fine-tuning the forming vascular plexus. [Copyright &y& Elsevier]

Abstract: A novel cryogenic optical-microscope system was developed in which the objective lens is set inside of the cryostat adiabatic vacuum space. Being isolated from the sample when it was cooled, the objective lens was maintained at room temperature during the cryogenic measurement. Therefore, the authors were able to use a color-aberration corrected objective lens with a numerical aperture of 0.9. The lens is equipped with an air vent for compatibility to the vacuum. The theoretically expected spatial resolutions of 0.39μm along the lateral direction and 1.3μm along the axial direction were achieved by the developed system. The system was applied to the observations of non-uniform distributions of the photosystems in the cells of a green alga, Chlamydomonas reinhardtii, at 94K. Gaussian decomposition analysis of the fluorescence spectra at all the pixels clearly demonstrated a non-uniform distribution of the two photosystems, as reflected in the variable ratios of the fluorescence intensities assigned to photosystem II and to those assigned to photosystem I. The system was also applied to the fluorescence spectroscopy of single isolated photosystem I complexes at 90K. The fluorescence, assigned to be emitted from a single photosystem I trimer, showed an intermittent fluctuation called blinking, which is typical for a fluorescence signal from a single molecule. The vibronic fluorescence bands at around 790nm were observed for single photosystem I trimers, suggesting that the color aberration is not serious up to the 800nm spectral region. [Copyright &y& Elsevier]

Highlights: [•] We describe methods for high-content drug screening in 3D culture systems with OCT. [•] The creation of an example time-lapse OCT setup is described. [•] Example results from a set of time-lapse OCT experiments are presented and analyzed. [Copyright &y& Elsevier]

Highlights: [•] A method is described to accurately subtract background in intensity-based images. [•] The method is successful under highly challenging measurement conditions. [•] High throughput FRET determination of androgen receptor structure is enabled. [•] Different steroids had similar effects on different androgen receptor activities. [Copyright &y& Elsevier]

Abstract: Intra-oral scanning technology is a very fast-growing field in dentistry since it responds to the need of an accurate three-dimensional mapping of the mouth, as required in a large number of procedures such as restorative dentistry and orthodontics. Nowadays, more than 10 intra-oral scanning devices for restorative dentistry have been developed all over the world even if only some of those devices are currently available on the market. All the existing intraoral scanners try to face with problems and disadvantages of traditional impression fabrication process and are based on different non-contact optical technologies and principles. The aim of this publication is to provide an extensive review of existing intraoral scanners for restorative dentistry evaluating their working principles, features and performances. [Copyright &y& Elsevier]

Abstract: This review is aimed at presenting the state-of-the-art of time domain (TD) functional near-infrared spectroscopy (fNIRS). We first introduce the physical principles, the basics of modeling and data analysis. Basic instrumentation components (light sources, detection techniques, and delivery and collection systems) of a TD fNIRS system are described. A survey of past, existing and next generation TD fNIRS systems used for research and clinical studies is presented. Performance assessment of TD fNIRS systems and standardization issues are also discussed. Main strengths and weakness of TD fNIRS are highlighted, also in comparison with continuous wave (CW) fNIRS. Issues like quantification of the hemodynamic response, penetration depth, depth selectivity, spatial resolution and contrast-to-noise ratio are critically examined, with the help of experimental results performed on phantoms or in vivo. Finally we give an account on the technological developments that would pave the way for a broader use of TD fNIRS in the neuroimaging community. [Copyright &y& Elsevier]

Highlights: [•] Specimen holders were developed for light-microscope observation. [•] They allow multiple-axis rotation with small-angle control. [•] Specimen tilting and rotation can be corrected while viewing. [•] They are easily manufactured and installed on a conventional microscope stage. [ABSTRACT FROM AUTHOR]

Highlights: [•] Inverted pyramidal neurons can be targeted for in vitro electrophysiology. [•] Inverted neurons are different from neighboring upright neurons. [•] Inverted neurons in the mouse neocortex differ from those found in the rat. [ABSTRACT FROM AUTHOR]

Abstract: Cardiac remodeling resulting from impairment of myocardial integrity leads to heart failure, through still incompletely understood mechanisms. The fibroblast growth factor (FGF) system has been implicated in tissue maintenance, but its role in the adult heart is not well defined. We hypothesized that the FGF system plays a role in the maintenance of cardiac homeostasis, and the impairment of cardiomyocyte FGF signaling leads to pathological cardiac remodeling. We showed that FGF signaling is required for connexin 43 (Cx43) localization at cell–cell contacts in isolated cardiomyocytes and COS7 cells. Lack of FGF signaling led to decreased Cx43 phosphorylation at serines 325/328/330 (S325/328/330), sites known to be important for assembly of gap junctions. Cx43 instability induced by FGF inhibition was restored by the Cx43 S325/328/330 phospho-mimetic mutant, suggesting FGF-dependent phosphorylation of these sites. Consistent with these in vitro findings, cardiomyocyte-specific inhibition of FGF signaling in adult mice demonstrated mislocalization of Cx43 at intercalated discs, whereas localization of N-cadherin and desmoplakin was not affected. This led to premature death resulting from impaired cardiac remodeling. We conclude that cardiomyocyte FGF signaling is essential for cardiomyocyte homeostasis through phosphorylation of Cx43 at S325/328/330 residues which are important for the maintenance of gap junction. [Copyright &y& Elsevier]

Highlights: [•] Immunocytochemical localization of glycine in CA1 pyramidal neurons. [•] Co-storage of glycine in glutamatergic presynaptic terminals. [•] Activity-dependent release of glycine. [•] Functional expression of synaptic and extrasynaptic GlyRs. [ABSTRACT FROM AUTHOR]

Abstract: The use of nanoparticulate zinc oxide (ZnO-NP) in sunscreens and other cosmetic products has raised public health concerns. The two key issues are the extent of exposure to ZnO-NP and the likely hazard after the application of ZnO-NP in sunscreen and cosmetic products to humans in vivo. Our aims were to assess exposure by the extent of ZnO-NP penetration into the viable epidermis and hazard by changes in the viable epidermal redox state for a number of topical products. Of particular interest is the role of the particle coating, formulation used, and the presence of any enhancers. Multiphoton tomography with fluorescence lifetime imaging microscopy (MPT–FLIM) was used to simultaneously observe ZnO-NP penetration and potential metabolic changes within the viable epidermis of human volunteers after topical application of various ZnO-NP products. Coated and uncoated ZnO-NP remained in the superficial layers of the SC and in the skin furrows. We observed limited penetration of coated ZnO-NP dispersed in a water-in-oil emulsion formulation, which was predominantly localized adjacent to the skin furrow. However, the presence of ZnO-NP in the viable epidermis did not alter the metabolic state or morphology of the cells. In summary, our data suggest that some limited penetration of coated and uncoated ZnO-NP may occur into viable stratum granulosum epidermis adjacent to furrows, but that the extent is not sufficient to affect the redox state of those viable cells. [Copyright &y& Elsevier]

Highlights: [•] Fatigue resistance of diarylethene–polymer composites was tested with optical absorption and fluorescence methods upon repetitive UV–VIS irradiation. [•] Significant differences in fatigue were found in different polymeric matrices and in one-photon and two-photon excitation experiments. [•] Several explanations for fatigue resistance of the composites are proposed based on the physico-chemical properties of the diarylethenes and polymeric matrices. [Copyright &y& Elsevier]

It is especially necessary in the field of laser direct writing lithography to gain exact knowledge about the shape and characteristics of the utilized laser beam, whilst a homogeneous power distribution is an essential parameter for sufficient and reproducible results in surface structuring. A novel method is presented to characterize the power distribution of a focussed laser beam by scanning its cross-sectional plane with an optical fibre tip that is commonly used for scanning near field optical microscopy (SNOM). This novel method is capable of characterizing laser beams diverging from very small focal apertures with a high resolution. This method can improve the research and development (R&D) of either an academic institute or a player in the optical industry regarding such things as the development of the next generation of optical storage. In contrast to the established profiling techniques and commercial products, the field of application includes the characterization of beams diverging from the lenses of DVD or BluRay© devices with numerical apertures (NA) in the range of 0.6 up to 0.85. Laser beams emerging from modified optical pickup units (OPU) have been successfully characterized using this novel method. [ABSTRACT FROM AUTHOR]

We propose a poly vinylidene fluoride (PVDF)-clad graded index plastic optical fiber (GI POF) which exhibits excellent mechanical strength and low bending loss property. A main concern of PVDF-clad GI POFs is the bandwidth degradation due to its specific waveguide structure compared to the conventional poly-methyl-methacrylate (PMMA)-based GI POF. We design the index profile of PVDF-clad GI POFs to maintain high bandwidth under a restricted mode launch condition. However, when mode coupling exists in PVDF-clad GI POFs, the bandwidth can be degraded. Hence, for high bandwidth performance, we investigate a way to reduce the mode coupling in PVDF-clad GI POFs. We find that the fiber numerical aperture (NA) is a key factor in controlling the mode coupling. By adjusting the NA of the GI core region to be as high as 0.17, bandwidth higher than 2 GHz for 100 m distance is achieved by the PVDF-clad GI POF. In addition, the propagating mode properties of the optimized PVDF-clad GI POF are investigated, particularly when the fiber is statically bent, because such a fiber bending can enhance mode coupling. We find that the high bandwidth performance is maintained in the PVDF-clad GI POF, even under severe bending conditions if the GI core region has an NA of 0.17 [ABSTRACT FROM PUBLISHER]

Modal dispersion in plastic optical fibers with W-shaped refractive index profiles (W-shaped POFs) is investigated. The authors focus on the effect of the refractive index valley at the boundary of core and cladding on the group delay. In this paper, particularly, the relationship between the depth of the index valley and the modal dispersion is highlighted. In order to analyze the relationship precisely, the authors prepare the W-shaped POFs with a high numerical aperture (NA ∼ 0.25), which are expected to show the effect of W-shaped profile more clearly than the W-shaped POFs with an NA of 0.2. As a result, the modal dispersion is strongly dependent on the depth of the index valley, which means that the control of the index valley is required, in order for minimum modal dispersion. Furthermore, by evaluating the output pulsewidth from the W-shaped POFs, the authors design the optimum index valley for the maximum bandwidth performance. [ABSTRACT FROM PUBLISHER]

The waveguide structure of graded-index plastic optical fibers (GI POFs), such as index profile, numerical aperture (NA), and core diameter, is appropriately designed for eliminating bending losses, even under a severe bending condition. The bending loss of GI POFs under a severe bending condition is drastically reduced when the core diameter is smaller than 200 μm and when the NA is higher than 0.25. The bending loss of GI POFs even under a severe bending condition vanishes with a core diameter of 200 μm and an NA of 0.24. It is experimentally confirmed for the first time that the mode coupling due to the bending induces the bending loss. The mode coupling strength before the fiber is bent affects the bending loss seriously. Moreover, the mode-coupling strength is evaluated by the propagation constant difference Δβ between the adjacent modes. The Δβ value, which is a function of the core diameter and NA, affects the bending loss. Therefore, based on the calculation of the Δβ, we propose a guideline for the appropriate design of waveguide parameters for GI POF, in order to suppress the bending loss. [ABSTRACT FROM PUBLISHER]

This paper confirms that numerical aperture (NA) is a key factor in mode coupling [the energy transfer among propagating modes in multimode fibers (MMF)] and that providing a high NA is a viable solution to reduce mode coupling in graded-index plastic optical fibers (GI POFs). Furthermore, the authors propose a new refractive-index-profile design of GI POFs when only small mode groups are launched (restricted-launch condition), which is a combined profile with the index exponents lower and higher than optimum value for the core center and periphery, respectively. The advantage of the new index profile is investigated both experimentally and theoretically. Furthermore, it is verified that the high-bandwidth performance of GI POF with the new index profile under the restricted-launch condition is maintained even when statistical fiber bendings are added to the GI POF and when misalignment is caused at the optical coupling between the light source and the GI POF. [ABSTRACT FROM PUBLISHER]

Bending effects on bandwidth and loss of a graded-index polymer optical fiber (GI POF) were investigated, and those influences on the optical link performance were discussed simultaneously for the first time. The numerical apertures (NAs) of the GI POFs were deliberately varied from 0.154 to 0.292. A bending radius larger than 10 mm induced little mode coupling and little change in the bandwidth of the GI POF. A bending radius smaller than 10 mm caused degradation in the bandwidths of the higher NA GI POFs. On the other hand, in the lower NA GI POFs, even more severe bending could cause little change in their bandwidths. Thus, the lower NA GI POF seemed preferable in suppressing the bandwidth change. However, the higher NA GI POF exhibited the lower bending loss. The preferable NAs for both characteristics were completely opposite. Moreover, the bending loss under underfilled launch (UFL) could be lower than that under overfilled launch (OFL). On the other hand, the bending loss was equivalent to the bandwidth degradation in view of the link power penalty. Therefore, the bandwidth change and loss caused by the bending were the critical factors to optimize the optical link considering the link power budget. The high-NA GI POF with almost ideal refractive-index profile could provide stable high performance in overgigabit communication even under any bending conditions. [ABSTRACT FROM PUBLISHER]

Both endocannabinoids through cannabinoid receptor type I (CB1) receptors and dopamine through dopamine receptor type D1 receptors modulate postsynaptic inhibition in substantia nigra by changing GABA release from striatonigral terminals. By recording from visually identified pars compacta and pars reticulata neurons we searched for a possible co-release and interaction of endocannabinoids and dopamine. Depolarization of a neuron in pars reticulata or in pars compacta transiently suppressed evoked synaptic currents which were blocked by GABAA receptor antagonists (inhibitory postsynaptic currents [IPSCs]). This depolarization-induced suppression of inhibition (DSI) was abrogated by the cannabinoid CB1 receptor antagonist AM251 (1 μM). A correlation existed between the degree of DSI and the degree of reduction of evoked IPSCs by the CB1 receptor agonist WIN55,212–2 (1 μM). The cholinergic receptor agonist carbachol (0.5–5 μM) enhanced DSI, but suppression of spontaneous IPSCs was barely detectable pointing to the existence of GABA release sites without CB1 receptors. In dopamine, but not in GABAergic neurons DSI was enhanced by the dopamine D1 receptor antagonist SCH23390 (3–10 μM). Both the antagonist for CB1 receptors and the antagonist for dopamine D1 receptors enhanced or reduced, respectively, the amplitudes of evoked IPSCs. This tonic influence persisted if the receptor for the other ligand was blocked. We conclude that endocannabinoids and dopamine can be co-released. Retrograde signaling through endocannabinoids and dopamine changes inhibition independently from each other. Activation of dopamine D1 receptors emphasizes extrinsic inhibition and activation of CB1 receptors promotes intrinsic inhibition. [Copyright &y& Elsevier]

Previously, we discovered a novel type of depolarization wave in the embryonic chick brain by using a multiple-site optical recording technique with a fast voltage-sensitive dye. This depolarization wave traveled widely over almost all the region of the CNS. This profile has raised the possibility that the depolarization wave plays some global roles in development of the CNS, rather than contributing to a specific neuronal circuit formation. To obtain more information concerning this issue, in the present study, we examined whether the depolarization wave was triggered by various types of peripheral nerve inputs. Stimulation applied to the vagus, glossopharyngeal, cochlear and trigeminal nerves evoked widely spreading depolarization waves with similar spatiotemporal distribution patterns. The developmental sequence of wave expression was parallel to the development of the excitatory postsynaptic potentials in each sensory nucleus. The depolarization wave was accompanied by a Ca2+-wave, suggesting that not only electrical synchrony, but also large-scale Ca2+-transients may affect developmental processes in the embryonic brain. Furthermore, we found that the depolarization wave also occurred spontaneously. The waveform and distribution patterns of the spontaneous optical signals were similar to those of the cranial nerve-evoked depolarization wave.These results demonstrated that the depolarization wave in the embryonic chick brain is triggered by multiple sources of external and endogenous activity. This profile supports the idea that this depolarization wave may not serve as a simple regulator of specific neuronal circuit formation, but might play more global roles in CNS development. [Copyright &y& Elsevier]

In this paper, we demonstrate a new technology in which we use the near infrared (NIR) electro-optical device and projection method to measure the numerical aperture (NA) of NIR fiber. Using the optical coupler to let the NIR light enter into an optical fiber, the projection pattern is then measured at the distance of L, where the length L and the diameter W of the projection pattern area on screen is recorded. The NA of NIR fiber is computed from the recorded data. This is a fast method for testing NA and can measure the NA deviation to an accuracy of 0.01. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 582–584, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23161 [ABSTRACT FROM AUTHOR]

We investigated the way to reduce the mode coupling (the energy transfer among the propagating modes) in a multimode fiber. It strongly influences the bandwidth in the graded-index plastic optical fiber (GI POF), and it was found that the mode-coupling strength in the GI POF depended on the numerical aperture of the fiber. Moreover, we propose a new optimum waveguiding design of GI POFs when only small mode groups are launched [under filled launch condition (UFL)], which is expected in a real high-speed GI POF link. We demonstrate greater than 1-GHz transmission by a 250-m polymethylmethacrylate (PMMA-d8)-based GI POF under the UFL condition. [ABSTRACT FROM PUBLISHER]