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In this paper, a highly sensitive diabetes detection sensor based on photonic crystal fiber-gold plasmonic material is designed, proposed and analyzed. In this sensor, the application of a gold thin film increases the operating wavelength range (400 nm–1200 nm). The analyte, which is the cell, is placed outside the sensor and makes it easy to fabricate. The proposed sensor detects healthy and diabetic cells based on the refractive indices. Moreover, full-transistor modeling is presented to detect the probability of diabetes. In this model, healthy persons, persons with a low risk of diabetes and persons with a high risk of diabetes are diagnosed. Numerical results show that the proposed biosensor has a maximum amplitude sensitivity of 2127.7 RIU−1, amplitude resolution of 4.69 × 10−6 RIU, maximum wavelength sensitivity of 21 000 nm RIU−1 and wavelength resolution of 4.76 × 10−7 RIU. [ABSTRACT FROM AUTHOR]

In the design of photonic integrated circuits (PICs), the optical connections of the PIC surface, along with the electronic components of the chips, are significant issues. One of the optoelectronics components that utilizes these surface connections are electro-reflective modulators, consisting of an optical section and an electronic section. In this paper, a novel scheme of two-dimensional photonic crystals (PhCs) is presented for the optical and reflective sections of this device. This design is two-dimensional; thus, it has less volume than the current bulky structures. The finite element method is utilized to simulate and optimize the scheme of PhCs and gold layer parameters. Furthermore, optimization of design parameters is accomplished through the Nelder–Mead method. Moreover, the modeling and simulation of the proposed hybrid PhCs has been investigated according to the structural parameters with tolerance. These tolerances, related to the nanorods' radius and lattice constants, are considered to justify and vindicate the fabrication technology limitations and conditions. In the "on" state of the modulator, the light transmission ratio is 98% for a 903 nm wavelength with a 45° angle of deflection and incident light, nd the bandwidth is 20 nm. For an 897 nm wavelength with a 41° angle, the transmission ratio is 95%, and the bandwidth is 7 nm. [ABSTRACT FROM AUTHOR]

Although perovskite solar cells have shown outstanding photovoltaic performance, there are still various obstacles that limit their performance and that remain as significant challenges. Weak optical absorption rate in the infrared region is a significant drawback for this kind of solar cell. In this paper, Au@SiO2@Graphene nanoparticles (NPs) as nano-photonic inclusions in the perovskite layer are proposed and investigated theoretically. Unlike conventional nanoparticles, these NPs exhibit strong, multiple plasmon resonances at low energies. The effect of geometrical parameters, periodicity, and the location of the Au@SiO2@Graphene NPs in the perovskite layer upon the performance of the PSCs are investigated. Under improved conditions, an absorption enhancement of 32% is obtained compared to pristine devices. Also, the result attained from coupled optical-electrical simulation of the improved device demonstrated 20.05% power conversion efficiency. These improvements have been achieved due to the plasmonic near-field enhancement effects of Au@SiO2@Graphene nanoparticles along with increased light-scattering from these NPs. [ABSTRACT FROM AUTHOR]

In this paper, tunable and efficient absorbers are proposed based on graphene–metal nano structures. The designed structures are consisted of multi layers of graphene (ring- and plate-shaped) and gold (5*5 cells) on the background of silica. By introducing different ring-shaped graphene layers (one, two or three), the near unity absorption coefficient can be achieved. The effects of different parameters like the distance, radius and chemical potential (h1, Rin1, EfR1, h2, Rin2, EfR2, h3, Rin3, EfR3) on the absorption spectrum (wavelength and value) are also considered. The best resonant peak (near unity) is obtained for the structure with three ring-shaped graphene layers. The final proposed structure (with three rings) can be utilized as an effective sensor for detecting materials with different refractive indices (from 1. to 1.5) with sensitivity of 100 (nm/RIU). The designed structure can be applied as a strong absorber or sensitive sensor in nano-optical systems. [ABSTRACT FROM AUTHOR]

Intra-abdominal adhesions following surgery are a challenging problem in surgical practice. This study fabricated different thermoplastic polyurethane (TPU) nanofibers with different average diameters using the electrospinning method. The conditions were evaluated by scanning electron microscopy (SEM), atomic force microscope (AFM), and Fourier transform infrared spectrometer (FTIR) analysis. A static tensile test was applied using a strength testing device to assess the mechanical properties of the electrospun scaffolds. By changing the effective electrospinning parameters, the best quality of nanofibers could be achieved with the lowest bead numbers. The electrospun nanofibers were evaluated in vivo using a rat cecal abrasion model. The macroscopic evaluation and the microscopic study, including the degree of adhesion and inflammation, were investigated after three and five weeks. The resultant electrospun TPU nanofibers had diameters ranging from about 200 to 1000 nm. The diameters and morphology of the nanofibers were significantly affected by the concentration of polymer. Uniform TPU nanofibers without beads could be prepared by electrospinning through reasonable control of the process concentration. These nanofibers' biodegradability and antibacterial properties were investigated by weight loss measurement and microdilution methods, respectively. The purpose of this study was to provide electrospun nanofibers having biodegradability and antibacterial properties that prevent any adhesions or inflammation after pelvic and abdominal surgeries. The in vivo experiments revealed that electrospun TPU nanofibers reduced the degree of abdominal adhesions. The histopathological study confirmed only a small extent of inflammatory cell infiltration in the 8% and 10% TPU. Conclusively, nanofibers containing 8% TPU significantly decreased the incidence and severity of postsurgical adhesions, and it is expected to be used in clinical applications in the future. [ABSTRACT FROM AUTHOR]

A new technique for cancer therapy is Photo Thermal Therapy (PTT). In the PTT technique, photon energy is converted into heat via various operations to destroy malignant tumors. Carbon nanotubes (CNTs) have good optical absorption in the near-infrared (NIR) spectrum and could transform optical energy into heat to induce hyperthermia in the PTT method. In this study, CNTs were firstly oxidized (O-CNT) and then decorated with silver nanoparticles (Ag NPs). Polyethylene glycol (PEG) was utilized for wrapping the surface of CNTs (O-CNT/Ag-PEG). Coating of CNTs with Ag NPs and PEG was confirmed by XRD, FESEM, and TEM techniques. Results demonstrated that noble metal could increase optical absorption of CNTs and concurrently improve the efficacy of the PTT technique. Cell cytotoxicity study showed that O-CNT/Ag NPs were less cytotoxic than O-CNTs, and O-CNT/Ag-PEG had the lowest toxicity against HeLa, HepG2, and PC3 human cell lines. The efficacy of O-CNT/Ag-PEG NPs in destroying malignant melanoma tumors was evaluated through the PTT technique. A continuous wave NIR laser diode (λ = 808 nm, P = 2 W, and I = 2 W/cm2 ) irradiated the tumor sites for 8 min once in the period of the treatment. The tumors in cases receiving O-CNT/Ag-PEG were shrunk efficiently compared to laser treatment ones. Results of in-vivo studies demonstrated that O-CNT/Ag-PEG was a puissant candidate in extirpating malignant tumors in PTT method. [ABSTRACT FROM AUTHOR]

People's preferences for urban parks are influenced by the spatial and contextual characteristics of spaces, where landscapes form the main body of parks. The present study examined women's preferences for landscape spatial quality indicators (including coherence, mystery, complexity, legibility, prospect, and refuge) in two urban parks. Also, the study explored the impact of socio-economic variables such as age, income, and education on women's preferences. In this spirit, a photo survey was conducted among 178 women as park users in Tabriz in 2017. Descriptive analysis, factor analysis, and comparison tests such as one-way ANOVA were used to analyze the data. Based on the results, the highest preferences were for mystery, complexity, and prospect. The results also revealed that the preference for landscape spatial quality indicators (LSQIs) varies among different age groups, education levels, and income statuses, where middle-aged women show the highest preference toward all of the LSQIs. Similarly, perception of and preference for landscape were seen to increase with education level, with less educated women demonstrating the lowest preferences for LSQIs in a park environment. Also, women with low and high income levels had the highest preference for mystery, complexity, and prospect of LSQIs. The population of middle-aged residents is increasing, which renders it necessary for special attention to be paid to understanding their opinions and demands for public spaces, such as landscape quality. It was likewise confirmed that users' characteristics should be taken into account in planting design, particularly its spatial configurations in urban parks. [ABSTRACT FROM AUTHOR]

A novel designation of an all optical plasmonic-dielectric power splitter-filter based on 2-D square lattice photonic crystals (PhCs) is proposed. The structure is consisted of air, aluminum, silver and copper rods in silicon background. Photonic band gap (PBG) analysis and field distributions are obtained by plane wave expansion (PWE) and finite difference time domain (FDTD) methods, respectively. As electromagnetic (EM) wave is propagated, power levels lower than “0.4’’ are considered as “0’’ and higher than “0.5’’ as “1’’. For definite wavelengths, only one output port transfers the power. Therefore, the system acts as a power splitter and filter, simultaneously. The proposed structure can confine lightwave to sub-wavelength dimensions (of the order of nano meter) because the multiple plasmonic/dielectric combinations are utilized in this structure. As a result, this device can be operational in integrated optical circuits. [ABSTRACT FROM AUTHOR]

Objective(s): Photo-thermal therapy (PTT) is a therapeutic method in which photon energy is converted into heat to induce hyperthermia in malignant tumor cells. In this method, energy conversion is performed by nanoparticles (NPs) to enhance induced heat efficacy. The low-cytotoxicity and high optical absorbance of NPs used in this technique are very important. In the present study, titanium dioxide (TiO2) NPs were used as agents for PTT. For increasing water dispersibility and biocompatibility, polyethylene glycol (PEG)-TiO2 NPs (PEGylated TiO2 NPs) were synthesized and the effect of these NPs on reducing melanoma tumor size after PTT was experimentally assessed. Materials and Methods: To improve the dispersibility of TiO2 NPs in water, PEG was used for wrapping the surface of TiO2 NPs. The formation of a thin layer of PEG around the TiO2 NPs was confirmed through thermo-gravimetric analysis and transmission electron microscopy techniques. Forty female cancerous mice were divided into four equal groups and received treatment with NPs and a laser diode (λ = 808 nm, P = 2 W & I = 2 W/cm²) for seven min once in the period of the treatment. Results: Compared to the mice receiving only the laser therapy, the average tumor size in the mice receiving TiO2-PEG NPs with laser excitation treatment sharply decreased. Conclusion: The results of animal studies showed that PEGylated TiO2 NPs were exceptionally potent in destroying solid tumors in the PTT technique. [ABSTRACT FROM AUTHOR]

Photonic crystals (PhCs) are artificial dielectric nanostructure materials. In these structures, a periodic modulation of the material dielectric constant results in a photonic band gap (PBG). By employing defects in the photonic crystals, light can steer in specific direction. Consequently, defects are used in most of the PhC structures. In this work, a novel channel drop filter (CDF) based on two dimensional (2-D) photonic crystal with octagonal shaped structure is designed and numerically analyzed by using the finite difference time domain (FDTD) and plane wave expansion (PWE) techniques. The proposed filter is an octagonal shaped structure of Si rods between two waveguides; consisting of 19*18 silicon rods with the refractive index of 3.5 and rod radius of 0.16a; where a is a lattice constant and equals 0.6 μm. By analyzing the structure, wide ranges of TE photonic band gap (PBG) would be achieved. It will be stated that the proposed CDF has appropriate characteristics and could be used in the future wavelength division multiplexing (WDM) communication systems. [ABSTRACT FROM AUTHOR]

In this paper, a novel nano-plasmonic split-ring resonator filter is proposed and simulated. In this structure, split-ring resonator is situated between a T-shaped and a straight waveguide. Simulations are done based on Finite-Difference-Time Domain method. The filter is based on metal-insulator-metal (MIM) structure. Split-ring resonator, straight and T-shaped waveguides are consisted of air which are situated in a silver background. Effects of different structural parameters, such as the width of the straight waveguide, the distance between left waveguide and ring, T-shaped waveguide’s width and length and the split position on the transmission spectrum of the filter are being investigated. The proposed filter can confine light to sub-wavelength dimensions (of the order of nano-meter); therefore, it can be used in highly integrated optical circuits. Hence, by adjusting structural parameters, the best transmission peak value of 0.84 at 935 nm will be obtained which can be utilized in integrated optical communication systems. [ABSTRACT FROM AUTHOR]

Purpose: Plasmonic photo thermal therapy (PPTT) is a therapeutic method in which the photon energy is rapidly transformed into heat via a series of radiative and non-radiative phenomena to ablate cancer. Plasmonic NPs, such as silver NPs (Ag NPs), have considerable properties in optical absorbance. Furthermore, good thermal conductivity and cell penetration ability of carbon nanotubes (CNTs) could improve the efficacy of Ag NPs for PPTT. Decoration of the multi-walled carbon nanotubes (MWCNTs) with silver has been developed to enhance thermal conductivity of the MWCNT particles. Methods: The Ag NPs were decorated on the CNTs and the ability of these particles (CNT/Ag NPs) in reduction of melanoma tumor size after PTT was evaluated experimentally. For comparison, the PTT of silver nanorods (Ag NRs) and CNTs were investigated. The melanoma tumor was induced by injection of B16/F10 cell line to the inbred mice. Different NPs were injected into the tumors and then irradiated via laser diode (λ=670 nm, P=500 mW, and I= 3.5 W/cm²) at scheduled time. Results: Monitoring of tumor sizes showed that integration of CNTs with silver could enhance the optical absorption of CNTs and improve tumor destruction in PPTT technique. Conclusion: The CNT/Ag NPs could act as a potent agent in PPTT method in curing solid tumors. [ABSTRACT FROM AUTHOR]

An optical frequency-shift keying (FSK) demodulator with ultrasmall plasmonic nanorods that can filter the coherent optical frequency is developed. Since the filtering efficiency depends strongly on the position and number of the plasmonic nanorods in the array, binary teaching–learning-based optimization (BTLBO) algorithm is proposed to design an array of the plasmonic nanorods in order to achieve maximum absorption coefficient spectrum. In BTLBO, a group of learner consists of a matrix with binary entries; control the presence (‘1’) or the absence (‘0’) of the nanoparticles in the array. [ABSTRACT FROM PUBLISHER]

A novel silicon waveguide structure is proposed to simultaneous dispersion engineering of orthogonal modes. Ultra flat dispersion profiles are achieved for both the fundamental quasi-transverse- electric (TE) and transverse-magnetic (TM) modes by utilizing mode transition and anti-crossing effects. Dispersion tailoring is carried out for both modes by tuning the structural parameters of the waveguide. There is only a low dispersion of < ± 3.8 ps/(nm∙km) over a 576-nm and a 817-nm bandwidth for the fundamental quasi-TE and quasi-TM modes, respectively. The reduced dispersion of the modes prevents pulse broadening and intensity reduction in each of the modes. The nonlinear parameters of the modes, the group velocity mismatch, and the characteristic lengths of walk-off and dispersion for both modes are also studied. It is discussed that mode coupling is feasible before the temporal separation of the modes can take place. Therefore, the proposed waveguide can provide highly efficient implementation of photonic applications based on polarization effects. [ABSTRACT FROM AUTHOR]