Integration of biofuels intermediates production and nutrients recycling in the processing of a marine algae

The cost‐effective production of liquid biofuels from microalgae is limited by several factors such as recovery of the lipid fractions as well as nutrients management. Flash hydrolysis, a rapid hydrothermal process, has been successfully applied to fractionate the microalgal biomass into solid biofuels intermediates while recovering a large amount of the nutrients in the aqueous phase (hydrolyzate) in a continuous flow reactor. The aim of the work is to enhance the quality of a high‐ash containing marine algae Nannochloropsis gaditana as biofuel feedstock while recycling nutrients directly for algae cultivation. Characterization of products demonstrated an increase in extractable lipids from 33.5 to 65.5 wt % (dry basis) while retaining the same fatty acid methyl ester profile, in addition to diminution of more than 70 wt % of ash compared to raw microalgae. Moreover, the hydrolyzate was directly used to grow a microalga of the same genus. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1494–1502, 2017     

Vanillin Formation by Electrooxidation of Lignin on Stainless Steel Anode: Kinetics and By-Products

Galvanostatic electrooxidation runs on stainless steel (SS-304) anode were carried out on soda lignins from wheat straw and bagasse obtained from acidification of respective soda black liquors. Vanillin concentration, produced during electrooxidation, is found to increase, attain a maximum, and then decline. Pseudo-first-order specific reaction rate constants for lignin degradation in electrooxidation over SS-304 anode were found to be 0.0308 and 0.0368 h^?1, respectively, for the two lignin samples. Degradation of vanillin during electrooxidation was found to be of second order with respect to vanillin concentration with specific reaction rate constant being 0.0009 L/(mg h). A kinetic model was proposed based on series-parallel multiple reaction scheme using a fourth-order Runge–Kutta iteration to fit the time-dependent vanillin concentration during electrooxidation. It was proposed that a vanillin precursor was formed from the parent lignin macromolecule with a pseudo-first-order specific reaction rate constant of 0.03 h^?1 for wheat straw soda lignin and 0.036 h^?1 for bagasse soda lignin. The vanillin precursor subsequently converted to vanillin with a pseudo-first-order specific reaction rate constant of 0.044 h^?1. In addition to vanillin, 4-hydroxy-3,5-dimethoxyphenyl ethanone, and 1,2-benzenedicarboxylic acid were detected as major by-products. Interestingly, some aliphatic and aromatic hydrocarbons were also formed.     

A New Approximate Closed-Form Distribution and Performance Analysis of a Composite Weibull/Log-Normal Fading Channel

The presence of both the fading and shadowing effects (also called composite multipath/shadowed fading) is often encountered in a realistic radio propagation scenario, thus, making it necessary to consider the simultaneous effect of fading and shadowing on the received signal. The multipath effect is captured using models such as Rician, Nakagami-m, Weibull distribution and shadowing effect is modeled using Log-normal distribution. In this paper we present the closed-form expression of composite (Weibull/log-normal shadowed) fading using the efficient tool proposed by Holtzman. Using this result, the closed-form expression of combined (time-shared) shadowed/unshadowed fading is presented. The performance measures of fading communication systems such as probability density function of signal to noise ratio, amount of fading, outage probability (P_out) and channel capacity are analyzed and expressed in closed form.     

Reactivity of Hydroxamate Ions in Cationic Vesicular Media for the Cleavage of Carboxylate Esters

The hydrolysis of carboxylate esters viz. p‐nitrophenyl acetate (PNPA), p‐nitrophenyl butyrate (PNPB) and p‐nitrophenyl octanoate (PNPO) in the presence of cationic vesicles of the surfactant dioctadecyldimethylammonium bromide (DODAC) by different hydroxamate ions i.e. acetohydroxamate (AHA^?), benzohydroxamate (BHA^?) and salicylhydroxamate (SHA^?) were studied. The kinetic data was supported by spectrophotometric measurements. The effects of vesicular size on the reaction have been discussed. The differential reactivity under endo‐ and exovesicular conditions has also been evaluated. Critical vesicle concentrations (CVC) of cationic vesicular surfactants were determined from conductometric and fluorimetric measurements at 300 K. Fluorescence probe pyrene and pyrene‐1‐carboxaldehyde have been used for determination of CVC. Further, thermodynamic parameters viz. Standard Gibb's energy (?G°), enthalpy (?H°), and entropy (?S°) of vesicles has also been evaluated within a temperature range of 303.15–328.15 K.     

Ultralow loading Pt nanocatalysts prepared by atomic layer deposition on carbon aerogels

Using atomic layer deposition (ALD), we show that Pt nanoparticles can be deposited on the inner surfaces of carbon aerogels (CA). The resultant Pt-loaded materials exhibit high catalytic activity for the oxidation of CO even at loading levels as low as approximately 0.05 mg Pt/cm2. We observe a conversion efficiency of nearly 100% in the 150-250 degrees C temperatures range, and the total conversion rate seems to be limited only by the thermal stability of the CA support in ambient oxygen. The ALD approach described here is universal in nature, and can be applied to the design of new catalytic materials for a variety of applications, including fuel cells, hydrogen storage, pollution control, green chemistry, and liquid fuel production.     

A State-of-the-art Elliptic Curve Cryptographic Processor Operating in the Frequency Domain

We propose a novel area/time efficient elliptic curve cryptography (ECC) processor architecture which performs all finite field arithmetic operations in the discrete Fourier domain. The proposed architecture utilizes a class of optimal extension fields (OEF) GF(q ^m ) where the field characteristic is a Mersenne prime q = 2 ⁿ  − 1 and m = n. The main advantage of our architecture is that it achieves extension field modular multiplication in the discrete Fourier domain with only a linear number of base field GF(q) multiplications in addition to a quadratic number of simpler operations such as addition and bitwise rotation. We achieve an area between 25k and 50k equivalent gates for the implementations over OEFs of size 169, 289 and 361 bits. With its low area and high speed, the proposed architecture is well suited for ECC in small device environments such as sensor networks. The work at hand presents the first hardware implementation of a frequency domain multiplier suitable for ECC and the first hardware implementation of ECC in the frequency domain.

Synthesis and characterization of coordination polymers of polyesters with pendant amino groups

Oligomeric polyester, namely, poly(tetramethylene aspartate) (PTMA), was synthesized from D ,L -aspartic acid and 1,4-butanediol by a melt-condensation technique. Polyester–metal complexes were synthesized by the reaction of PTMA with hydrated acetates of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II), Mg(II), Ca(II), Pb(II), and Ce(IV) in DMSO. The polyester–metal complexes were characterized by elemental analysis, IR spectral studies, magnetic susceptibility measurements, and thermogravimetry. The metal ions were found to be six-coordinated with two water molecules as additional ligands besides oxygen and nitrogen atoms of polyester repeating units. Thermogravimetric analysis (TGA) showed that coordination polymers are thermally more stable than is polyester. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 69: 751–759, 1998     

Modification of Microstructure of Starch Extruded With Selected Lipids

Normal corn starch was extruded with palm, peanut and coconut oils; myristic, stearic and behenic acids and three monoglycerides in a C. W. Brabender single screw laboratory extruder at 140°C barrel temperature, 140rpm screw speed and 22% moisture content. Microstructure of extrudates was studied using a scanning electron mircocope. The pore size distribution, pore volumes and shear strengths of the extrudates were also studied. Addition of lipids resulted in modification of pore size distribution and pore volumes depending on the type of lipid. Complexing lipids gave lower pore volumes, smaller size pores, lower porosities and higher shear strengths of the extrudates. Porosity correlated well with the shear strength values.     

Novel anhydrous composite membranes based on sulfonated poly (ether ketone) and aprotic ionic liquids for high temperature polymer electrolyte membranes for fuel cell applications

Novel composite membranes were prepared using imidazolium type aprotic ionic liquids and sulfonated poly (ether ketone) (SPEK) as polymer matrix by solution casting process. All the prepared membranes were characterized for their thermal stability, mechanical properties, ion exchange capacity, proton conductivity and leaching out of ionic liquids in presence of water. Ionic liquid based membranes were more flexible than neat SPEK membrane due to the plasticization effect of ionic liquids. The interactions and compatibility occurring among components were investigated by vibration spectroscopy (FTIR ATR) and scanning electron microscopy respectively. The thermal stability of composite membranes was higher than unmodified membranes. The ion conductivity of composite membranes under anhydrous conditions was found to be dependent on temperature, type and concentration of ionic liquid in SPEK matrix. Ion conductivities of composite membranes under anhydrous condition were found to be up to two orders (∼100 times) higher than neat SPEK membrane and it was found to be ∼5 mS/cm at 140 °C for SPEK/OTf-70. These composite membranes can be successfully operated at temperatures ranging from 40 °C to 140 °C under anhydrous conditions.     

Synthesis of copper-ferrous (CuFe) nanowires via electrochemical method and its investigations as a fluid sensor

The special behaviour of nanowires with respect to electrical conductivity makes them suitable for sensing application. In this paper, we present a copper-ferrous (CuFe) nanowires based sensor for detection of chemicals. CuFe nanowires were synthesized by template-assisted electrochemical method. By optimizing the deposition parameters, continuous nanowires on a copper substrate were synthesized. The morphological and structural studies of the synthesized CuFe nanowires were carried out using scanning electron microscope (SEM) and X-ray diffraction (XRD). Substrates containing CuFe nanowires were moulded to form a capacitor. Different chemicals were used as dielectric in the capacitor which showed that the capacitance was a nonlinear function of the dielectric constant of fluid unlike the linear relation shown by conventional capacitors. This unique property of the nanowires based capacitors may be utilized for developing fluid sensors with improved sensitivity.