A Mode-Locked Soliton Erbium-Doped Fiber Laser with a Single-Walled Carbon Nanotube Poly-Ethylene Oxide Film Saturable Absorber

We present a simple, compact and low-cost mode-locked erbium-doped fiber laser （EDFL） using single-wMled carbon nanotubes （SWCNTs） embedded in a poly-ethylene oxide （PEO） thin film as a passive saturable absorber. The film is fabricated by using a prepared homogeneous SWCNT solution, which is mixed with a diluted PEO solution and cast onto a glass Petri dish to form, by evaporation, a thin film. The 50 μm-thick film is sandwiched between two fiber connectors to construct a saturable absorber, which is then integrated in an EDFL cavity to generate self-started stable soliton pulses operating at 1560.8nm. The soliton pulse starts to lase at a pump power threshold of 12.3mW with a repetition rate of 11.21MHz, a pulse width of 1.02ps, an average output power of 0.65 mW and a pulse energy of 57.98pJ.     

Mode-locked L-band bismuth–erbium fiber laser using carbon nanotubes

A passively mode-locked, bismuth–erbium-co-doped fiber (Bi-EDF) with a pulse width of 460 fs is proposed and demonstrated. A highly doped, 180-cm Bi-EDF with an erbium concentration of 3,250 ppm/wt and an absorption rate of 133 dB/m at 1,530 nm serves as the gain medium. The cavity is 11.6 m long with an overall group velocity dispersion of +0.063 ps². The output pulses have a repetition rate, average output power, pulse energy and peak power of 11.18 MHz, 5 mW, 448 pJ and 1 kW, respectively. The system has a high beam quality and a narrow pulse width output in the L-band region.     

Effect of roasting conditions on color development and Fourier transform infrared spectroscopy (FTIR-ATR) analysis of Malaysian-grown tropical almond nuts (<Emphasis Type="Italic">Terminalia catappa</Emphasis> L.)

Background

Proper roasting is crucial to flavor, color, and texture development in the final product. In recent years, several research studies have been carried out to establish the best optimum roasting conditions for some common edible nuts such as; hazelnut, peanut, and pistachio nut. Although roasting is an important process for nuts and oilseeds, there is little or no information on the development of color, aroma, and textural changes in Terminalia catappa nuts during roasting.

Results

Results showed that color formation and browning index were significantly (P < 0.05) influenced by the roasting temperature and time of roasting. However, the fracturability of nuts was significantly (P < 0.05) affected by both temperature of roasting and time as well as pH. The optimized results showed that the best response was reached when the roasting time was 29.9 min, roasting temperature 174.5°C, and pH 6.08, respectively. Moreover, the 3400–15603400–1560°Cm^-1 carbonyl region for carboxylic acid, alkenes, esters, and amines was found to provide a flavor-print of the roasted tropical almond nut. While, increase in temperature did not produce new carbonyl compounds, it however led to higher concentration of compounds. Scanning electron microscopy of the almond nuts showed that the starch granules were embedded in tissues.

Conclusion

These results showed that roasting temperature and time of roasting were the main variables that significantly affected the physicochemical properties of roasted tropical almond nuts. Moreover the flavor-prints for the roasted nut were produced in the 3400–1560°Cm^-1 carbonyl region.

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Graphical Abstract Effect of roasting conditions on fracturability and structural morphology of tropical almond nuts (T. catappa).

     

Influence of Composition of Nickel-Iron Nanoparticles for Abiotic CO2 Conversion to Early Prebiotic Organics

Abiotic synthesis of formate and short hydrocarbons takes place in serpentinizing vents where some members of vent microbial communities live on abiotic formate as their main carbon source. To better understand the catalytic properties of Ni−Fe minerals that naturally exist in hydrothermal vents, we have investigated the ability of synthetic Ni−Fe based nanoparticular solids to catalyze the H₂-dependent reduction of CO₂, the first step required for the beginning of pre-biotic chemistry. Mono and bimetallic Ni−Fe nanoparticles with varied Ni-to-Fe ratios transform CO₂ and H₂ into intermediates and products of the acetyl-coenzyme A pathway—formate, acetate, and pyruvate—in mM range under mild hydrothermal conditions. Furthermore, Ni−Fe catalysts converted CO₂ to similar products without molecular H₂ by using water as a hydrogen source. Both CO₂ chemisorption analysis and post-reaction characterization of materials indicate that Ni and Fe metals play complementary roles for CO₂ fixation.     

On the Convergence of Bernstein-Stancu Polynomials in the Variation Seminorm

This article studies the variation detracting property and rate of approximation of the Bernstein-Stancu polynomials in the space of functions of bounded variation with respect to the variation seminorm. Moreover, we will present Voronovskaya-type theorems for Bernstein-Stancu polynomials B_{n, α, β}f and for the first derivative of these polynomials. Finally we include some graphical examples.     

Sol–gel synthesis and characterization of Li<Subscript>2</Subscript>CO<Subscript>3</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composite solid electrolytes

Composite solid electrolytes in the system (1???x)Li₂CO₃–xAl₂O₃, with x?=?0.0–0.5 (mole), were synthesized by a sol–gel method. The synthesis carried out at low temperature resulted in voluminous and fluffy products. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy/energy-dispersive X-ray, Fourier transform infrared spectroscopy and AC impedance spectroscopy. Structural analysis of the samples showed an amorphous feature of Li₂CO₃ and traces of α-LiAlO₂, γ-LiAlO₂ and LiAl₅O₈. The prepared composite samples possess high ionic conductivities at 130–180 °C on account of the presence of lithium aluminates as well as the formation of a high concentration of an amorphous phase of Li₂CO₃ via this sol–gel preparative technique.     

Heterogeneous Membrane and Coated Wire Type Electrode with Chitosan as Ionophore in the Potentiometric Determination of Glutamate: Comparative Study

This study reports on two types of glutamate sensors based on chitosan, i) heterogeneous membrane and ii) coated wire (CWE). The linearity ranges are: i) membrane, 1.0×10^?5 to 1.0×10^?1 M and ii) CWE, 1.0×10^?5 to 1.0×10^?3 M. The LODs, and pH ranges are i) membrane, 5.0×10^?6 M and 4–8 and ii) CWE, 1.0×10^?5 M and 3–5, respectively. The presence of ionic species normally found in foodstuffs did not interfere in both electrodes. Interference in CWE was minimized by prior dilution of the sample. The CWE was further investigated for on‐line analysis. The material for proposed electrodes was cheaper and environmental friendly. Hence, they were suggested as alternative tools for the analysis of glutamate.     

Development of Prototype Wireless Transmission Measurement for Glucose in Subcutaneous and Brain Striatum

Monitoring of glucose in subcutaneous and brain striatum have been extensively studied in the past. While biocompatibility was one of the limitations, others included the messy measuring equipments preclude monitoring in a complex environment. This study tried to establish an amperometric measurement of glucose in pre‐ and post‐insulin‐administration on diabetic and hyperglycemia rats via wireless. The results have indicated that the wireless sensing kit used was capable of monitoring glucose in both subcutaneous and brain. The physiological data have also shown a new insight on the fabrication of implantable glucose sensors.     

Phase behavior of symmetric ternary block copolymer-homopolymer blends in thin films and on chemically patterned surfaces

The phase diagram of symmetric ternary blends of diblock copolymers and homopolymers in thin films was determined as a function of increasing volume fraction of homopolymer (phi(H)) and was similar to that for these materials in the bulk. Blends with compositions in the lamellar region of the diagram (phi(H)< or =0.4) could be directed to assemble into ordered lamellar arrays on chemically striped surfaces if the characteristic blend dimension (L(B)) and the period of the stripes (L(S)) were commensurate such that L(S)=L(B)+/-0.10L(B). Blends with compositions in the microemulsion region of the diagram (phi(H) approximately 0.6) assembled into defect-free lamellar phases on patterned surfaces with L(S)> or =L(B), but formed coexisting lamellar (with period L(S)) and homopolymer-rich phases when L(S)相似文献   

Regenerated fibre Bragg grating fabricated on high germanium concentration photosensitive fibre for sensing at high temperature

A Regenerated Fibre Bragg Grating (RFBG), with repeatable high temperature response between 400 °C–1200 °C, has been demonstrated using a hydrogen-loaded, highly germanium-doped, photosensitive fibre. A wavelength shifts of as much as 20 nm is attained during temperature calibration up to 1300 °C. A large temperature response of 17 pm/°C is obtained from the RFBG, with very good repeatability.