Programmable high-speed polarization multiplexed optical scanner

A fast digital-analog control polarization-based optical scanner with complete three-dimensional beam-forming programmability is described. Its features include low power consumption and large-aperture liquid-crystal-based optics, digital repeatability, and time-multiplexed accurate analog beam forming. Analog frequency and amplitude control of the nematic liquid-crystal beam-former cells permits continuous fine-scan programmability over a 0.66-mrad horizontal deflection, a 0.75 mrad vertical deflection, and an infinity-to-1.84-m focal-length longitudinal scan. First demonstrations included an 8-point volumetric scan and a 2-bit digital lens scan, both at 1310 nm, with a 35-micros random-access time.     

Acousto-optic device-based high-speed high-isolation photonic switching fabric for signal processing

A high-speed, switched, binary photonic switching fabric based on two acousto-optic devices arranged in a compact self-aligning (by acousto-optic device-based Bragg matching) optical geometry is introduced for photonic signal processing and control. This fabric has the unique capability to provide simultaneously both high switching speeds and high optical isolation, a critical need for advanced low-noise high-speed signal-processing applications. The proof-of-concept experimental fabric demonstrated nearly 60% light throughput, a 39-dB optical isolation level for both states of the switching fabric, and a 138-ns switching time.     

Synthesis, Characterization, and Electrochemical Properties of a Novel Macrocylic Ligand and its Transition Metal Complexes

 2,3-Dibromo-6,7,13,14,15,16,22,23-octahydro-14,15-bis-(hydroxyimino)-tribenzo [e,k,q][1,4,7,10,13,16]tetraoxadiazacyclohexadecine (LH₄) was prepared by condensation of 1,2-bis-(2′-aminophenoxyethoxy)-4,5-dibromobenzene with cyanogen-di-N-oxide. Mono-, di-, and trinuclear transition metal complexes of this ligand ((LH₃)₂Ni, (LH₃)₂Zn, (LH₃)₂Co, (LH₃)₂Cu, (LH₃)₂Fe, (LH₃)₂(UO₂)₂(OH)₂, (LH)₂Cu₃, (LH)₂Co₃) were synthesized under basic conditions. The electrochemical properties of the mono- and dinuclear complexes were studied by cyclic voltammetry in DMSO solution containing TBAP. The results showed that all redox processes are based on the metal center and the oxime ligands stabilize the Ni(III), Fe(III), Co(III), and Cu(III) species formed during oxidation. The Fe(II) and U(VI)O₂ complexes displayed a different behaviour: a reduction peak with the corresponding anodic signal during the reverse scan was observed. The oxime moiety also stabilizes U(V)O₂ which forms during the reduction process of the uranyl complex. Cu(II) was adsorbed on the electrode surface upon scanning cathodically.     

A photoelectron spectroscopic study of proximity effects in 8,11-disubstituted pentacyclo(5.4.0.02.6 .03,10 .05,9) Undecanes

Photoelectron spectra of six 8,11-disubstituted pentacycloundecanes (1, 3 - 7) are reported; the results suggest that the through-space interaction betweeen unsaturation centers in 1 and 3 dominates over the through-bond interaction mechanism.     

Separation of Linear and Branched Alkanes Using Host–Guest Complexation of Cyclic and Branched Alkane Vapors by Crystal State Pillar[6]arene

Activated crystals of pillar[6]arene produced by removing the solvent upon heating were able to take up branched and cyclic alkane vapors as a consequence of their gate‐opening behavior. The uptake of branched and cyclic alkane vapors by the activated crystals of pillar[6]arene induced a crystal transformation to form one‐dimensional channel structures. However, the activated crystals of pillar[6]arene hardly took up linear alkane vapors because the cavity size of pillar[6]arene is too large to form stable complexes with linear alkanes. This shape‐selective uptake behavior of pillar[6]arene was further utilized for improving the research octane number of an alkane mixture of isooctane and n‐heptane: interestingly, the research octane number was dramatically improved from a low research octane number (17 %) to a high research octane number (>99 %) using the activated crystals of pillar[6]arene.     

2D numerical contributions for the study of non-cohesive sediment transport beneath tidal bores

2D numerical simulations of tidal bores were obtained using the OpenFOAM CFD software to solve the Navier–Stokes equations by means of the Finite Volume Method by applying a LES turbulence model. The trajectories of non-cohesive sediment particles beneath tidal bores were estimated using a tracker method. Using the fourth order Runge–Kutta scheme, the tracker method solves the Maxey and Riley equations, which requires the knowledge of the velocity field at time t. From 2D numerical simulations of tidal bores, we proposed a classification of tidal bores with respect to the Froude number Fr (or r the ratio of water depths). For a Froude number $1<Fr<1.43$ ($1<r<1.57$), the tidal bore is undular. For a Froude number $1.43<Fr<1.57$ ($1.57<r<1.75$), the tidal bore is partially breaking, which is similar to the transitional tidal bore defined by Furgerot (2014). And for a Froude number $Fr>1.57$ ($r>1.75$), the tidal bore is totally breaking. The numerical results of trajectories of non-cohesive sediment particles are similar to the type of trajectories given by the analytical model proposed by Chen et al. (2012) with some modifications to take into account the effects of gravity, elevation, and attenuation. The parameters of modified Chen's model, ${\beta }_1$, ${\beta }_2$ and ${\beta }_3$, are linearly proportional to the Froude number Fr. This is because the level of turbulence for undular tidal bores is low. The flow induced by an undular tidal bore is not complex. This physical phenomenon is quasi linear. The parameter ${\beta }_1$, related to the front celerity of the undular tidal bore, decreases when the Froude number Fr increases. The parameter ${\beta }_2$, related to the elevation, increases when the Froude number Fr increases. And the parameter ${\beta }_3$, related to the attenuation of the secondary waves, increases when the Froude number Fr increases.     

Matrix interferences in the determination of trace elements in waste waters by inductively coupled plasma atomic emission spectrometry with ultrasonic nebulization

The use of inductively coupled plasma atomic emission spectrometry with ultrasonic nebulization (USN-ICP-AES) for determining Ag, Al, As, Ba, Bi, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Sb, Sr, V and Zn in complex matrices of Ca, Na, K and P in waste waters is described. Generally, depressions in the analyte emission intensity occur in the presence of concomitants. Matrix interferences can be minimized by increasing the operating power and lowering the carrier gas flow rate. However, the enhancement of the signal-to-background ratios (SBRs) shows an opposite trend. Therefore, routine analyses were performed at a compromise power setting of 1350 W, a carrier gas flow rate of 0.8 L min^–1 and an observation height of 14 mm above the load coil and using a matrix matched calibration procedure. Limits of detection (LODs) at chosen operating conditions were at μg L^–1 levels for most of the elements studied, including mercury when KBr is added to the analyte solution to enhance sensitivity. LODs were not significantly changed in the presence of matrix elements. Recoveries for the majority of added elements from spiked waste water samples are between 93 and 105% using a matrix matched calibration. Received: 13 January 2000 / Revised: 10 April 2000 / Accepted: 18 April 2000     

Fault-tolerant polarization-insensitive photonic delay line architectures using two-dimensional digital micromirror devices

A binary multichannel photonic delay line (PDL) module is introduced that gives balanced loss switched states and a polarization-insensitive operation via the use of binary operation Digital Micromirror Devices (DMDs). Experimental demonstration of a DMD-based PDL architecture is performed for a 6.84-ns time delay design. Experimental results include a 25-beam feed interchannel crosstalk test indicating a <−60 dB optical interchannel crosstalk level for a 0.381 mm interchannel distance in the multichannel PDL. An average optical signal-to-leakage noise ratio of 35.33 dB is measured for this PDL. A butterfly design PDL optical architecture is proposed for minimizing loss and improving assembly accuracy. These DMD-based variable PDLs can be used in applications ranging from radio frequency (RF) fiber-optic signal processing systems to adaptive optics for astronomical and laser radar arrays.     

Acoustic Properties of Micro-Perforated Panels Made from Oil Palm Empty Fruit Bunch Fiber Reinforced Polylactic Acid

This paper presents the development and performance of micro-perforated panels (MPP) from natural fiber reinforced composites. The MPP is made of Polylactic Acid (PLA) reinforced with Oil Palm Empty Fruit Bunch Fiber (OPEFBF). The investigation was made by varying the fiber density, air gap, and perforation ratio to observe the effect on the Sound Absorption Coefficient (SAC) through the experiment in an impedance tube. It is found that the peak level of SAC is not affected, but the peak frequency shifts to lower frequency when the fiber density is increased. This phenomenon might be due to the presence of porosity in the inner wall of the holes. Increasing or decreasing the air gap and perforation ratio shifts the peaks of acoustic absorption either way.     

The Amine Functionalized Sugarcane Bagasse Biocomposites as Magnetically Adsorbent for Contaminants Removal in Aqueous Solution

The method of solvothermal by one-step operation has been performed to synthesize of magnetic amine-functionalized sugarcane bagasse biocomposites (SB-MH). The obtained SB-MH contains 62.34% of Fe, 17.8 mmol/g of amine, and a magnetic property of 19.46 emu/g. The biocomposite surface area increased significantly from 1.617 to 25.789 m²/g after amine functionalization. The optimum condition of SB-MH used for Pb(II) ion removal was achieved at pH 5 for 360 min with adsorption capacity of 203.522 mg/g. The pseudo 2nd order was well-fitted to the model of Pb(II) ion adsorption. Meanwhile, other contaminant parameters number of Chemical Oxygen Demand (COD), Total Suspended Solid (TSS), and dye in wastewater were also remarkably reduced by about 74.4%, 88.0%, and 96.7%, respectively. The reusability of SB-MH with 4th repetitions showed only a slight decrease in performance of 5%. Therefore, the proposed magnetic amine-functionalized sugarcane bagasse biocomposites lead to a very potential adsorbent implemented in high scale due to high surface area, easy separation, stable materials and capability to adsorb contaminants from aqueous solution.