Design and optimization of high-performance microring-based uni-traveling carrier photodiode for WDM optical systems

This paper presents the design principles of a novel optimized microring-based uni-traveling carrier photodiode (MR-UTC-PD), for wavelength division multiplexing (WDM) optical systems. The fundamental parameters for output characteristics such as quantum efficiency and 3-dB bandwidth of MR-UTC-PD are discussed. We analyze the effects of basic parameters as effective ring radius, definite coupling condition and the suitable cross section on the MR-UTC-PD main characteristics for high performance of the device. It is shown that the maximum quantum efficiency and most efficient performance of the device can be obtained at critical coupling condition. We show that the maximum 3-dB bandwidth and an efficient approach for high bandwidth-efficiency product can be achieved at overcoupling condition. In this regard, some design curves are presented for the optimized MR-UTC-PD.     

Effective Mass of Radion via GW Mechanism with a Non-Minimally Coupled Bulk Scalar Field

In the Randall-Sundrum braneworld scenario via the Goldberger-Wise mechanism, the effective mass of 4D radion, where the bulk scalar field is coupled to 5D gravity, has been investigated in two different case of the self-coupling constants, infinite and finite cases. It is shown that in the finite case, the modulus parameter should be greater than the finite coupling constants.     

Use of nanoporous Na+-montmorillonite sulfonic acid (SANM) as an eco-benign, efficient and reusable solid acid catalyst for the one-pot synthesis of 14-aryl-14-H-dibenzo[a,j]xanthenes and 1,8-dioxo-dodecahydroxanthene derivatives

Nanoporous Na⁺-montmorillonite sulfonic acid was found to be an efficient and green catalyst for the synthesis of various 14-aryl-14H-dibenzo[a,j]xanthenes and 1,8-dioxo-dodecahydroxanthene derivatives by the reaction of aldehydes with 2-naphthol and 1,3-cyclohexanedione, respectively. This novel synthetic method has the advantages of high yields, short reaction times and recyclability of the catalyst, simplicity and easy workup compared to the conventional methods reported in the literature.     

Solubility Data of Diazepam in Binary and Ternary Mixtures of PEGs 200 and 400 with N-Methyl Pyrrolidone and Water at 298.2 K: Experimental Data and Modeling

Experimental solubilities of diazepam in binary and ternary solvents of polyethylene glycols 200 and 400 with N-methyl pyrrolidone and water at T = 298.2 K are reported. The Jouyban–Acree model was used to fit solubility data of diazepam in the binary and ternary solvent mixtures (106 data points) in which the overall mean relative deviations (OMRD %) is 13.1 % and the prediction OMRD % is 31.7 %. The combined version of the Jouyban–Acree model with Hansen solubility parameters was used for fitting and predicting the solubility data and the OMRDs % are 10.0 and 20.8 %, respectively. Also, the previously proposed trained versions of the Jouyban–Acree model were used for predicting the reported data in this work and all results are listed in the tables. The density of the solute-free solvent mixtures were measured and employed to calculate the constants of the Jouyban–Acree model and then the densities of the saturated solutions were predicted.     

Physical and Rheological Characteristics of Emulsion Model Structures Containing Iranian Tragacanth Gum and Oleic Acid

The physical and rheological properties of oil in water model emulsion systems containing Iranian tragacanth gum (TG) (0.5, 1 g/100 ml emulsions), whey protein isolate (WPI) (2, 4 g/100 ml emulsions), and oleic acid (5, 10 ml/100 ml emulsions) were investigated for droplet-size distribution, creaming index, and rheological properties of emulsions. The shear-thinning behavior of all dispersions was modeled using power law, Cross, and Ellis models. The power law model described the flow behavior of dispersions for its lowest standard error (0.29) and highest determination coefficient (R²) (0.99). Rheological investigation showed that both loss (G″) and storage (G′) modules increased as gum and oil content increased. Delta degree was 0.1 and increased as frequency increased, indicating that liquid-like viscose behavior dominated solid-like elastic behavior. Droplet-size distribution was measured by light scattering and microscopic observations revealed a flocculated system. Gum, WPI, and oil contents decreased the emulsion creaming index with gum concentration having the greatest effect.     

Contact angle hysteresis in multiphase systems

Contact angle (CA) hysteresis is the difference between the maximum (advancing) and minimum (receding) water CA. Hysteresis is caused by adhesion hysteresis in the solid–water contact area (2D effect) and by pinning of the solid–water–air triple line due to the surface roughness (1D effect). In this work, we show that CA hysteresis is present also in more complex systems, such as an organic liquid (oil) in contact with a solid immersed in water. In order to decouple the 1D and 2D effects, we study CA hysteresis in solid–water–air (droplet), solid–air–water (bubble), solid–water–oil, and solid–water–air–oil systems involving rough and microstructured surfaces. The comparative analysis of these systems allows decoupling the 1D and 2D effects as well as hydrogen bonding and entropic forces (water–air tension) and dispersion forces (oil–air tension).     

Ligandless-ultrasound-assisted emulsification microextraction followed by inductively coupled plasma-optical emission spectrometry for simultaneous determination of heavy metals in water samples

In this study, a simple and efficient method of ligandless-ultrasound-assisted emulsification microextraction (LL-USAEME) followed by inductively coupled plasma-optical emission spectrometry (ICP-OES) has been developed for simultaneous extraction, preconcentration and determination of manganese, cadmium, cobalt and nickel in water samples. In the proposed approach, tetrachloroethylene was selected as extraction solvent. The effect of important experimental factors such as volume of extraction solvent, pH, sonication time, salt concentration, and temperature was investigated by using a fractional factorial design (2^5?1) to identify important factors and their interactions. In the next step, a Box-Behnken design (BBD) was applied for optimisation of significant factors. The obtained optimal conditions were: 30?µL for extraction solvent, 12 for pH, 5?min for sonication time, and 5% w/v for salt concentration. The limits of detections (LODs) for Cd(II), Co(II), Mn(II) and Ni(II) were 0.20, 0.13, 0.21 and 0.28?µg?L^?1, respectively. Relative standard deviations (RSD, C?=?200.0?µg?L^?1, n?=?9) were between 3.4–7.5% and the calibration graphs were linear in the range of 0.25 to 1000.0?µg?L^?1 for Mn, 0.5–1000.0?µg?L^?1 for Co and Ni and 1.0–250.0?µg?L^?1 for Cd. The determination coefficients (R ²) of the calibration curves for the analytes were in the range of 0.993 to 0.999. The proposed method was validated by using two certified reference materials, and also the method was applied successfully for the determination of heavy metals in different real water samples.     

“Grafting through” approach for synthesis of polystyrene/silica aerogel nanocomposites by in situ reversible addition-fragmentation chain transfer polymerization

Aerogel/polystyrene nanocomposites with mixed free and aerogel-attached polystyrene chains were synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization. 3-methacryloxypropyldimethylchlorosilane containing a double bond, which could be incorporated into polystyrene chains by a “grafting through” approach, was used as an aerogel modifier. Kinetics of RAFT polymerization of styrene in the presence of modified silica aerogel was studied by monitoring conversion and molar mass values. To further study, attached polymers were detached and their molecular characteristics were compared to free chains. According to results, the presence of silica aerogel particles has a sensible influence on polymerization kinetic and more aerogels result in decreased polymerization rate and conversion. The dispersity (Ð) of polymer chains increased by the addition of silica aerogel. In the case of aerogel-attached polystyrene chains, number-averaged molar mass values were slightly lower than that of free chains. Also, thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) techniques were used to observe the effect of loading on thermal properties of synthesized nanocomposites.     

Energy and exergy analysis of a novel turbo-compounding system for supercharging and mild hybridization of a gasoline engine

Journal of Thermal Analysis and Calorimetry - Number of hybrid vehicles has increased around the world significantly. Automotive industry is utilizing the hybridization of the powertrain system to...