The Utilization of Post-chlorinated Municipal Domestic Wastewater for Biomass and Lipid Production by <Emphasis Type="Italic">Chlorella</Emphasis> spp. Under Batch Conditions

South Africa has a rich microalgal biodiversity which has the potential to be used for renewable bio-fuel production in the region. Bioprospecting for oleaginous microalgae in KwaZulu Natal Province, South Africa, resulted in the establishment of a microalgal culture collection system for alternative energy research in the country. A potential hyper-lipid-producing Chlorella spp. strain was isolated, purified, and cultured in supplemented post-chlorinated wastewater for biomass and lipid production at the laboratory scale under batch mode. The microalgal strain was cultivated in different strengths of BG-11 media supplemented with wastewater from a local municipal domestic wastewater treatment plant. The Chlorella spp. was grown using ambient dissolved carbon dioxide in shake flasks under photosynthetically active radiation (±120 μmolm⁻²s⁻¹). Microalgal biomass and lipid productivity were monitored at 24-h intervals in the batch mode. The microalgal biomass was analyzed by direct light microscopy and indirectly by spectrophotometry at 600 nm, and the lipids were extracted and quantified. The growth rate of the Chlorella spp. was enhanced in post-chlorinated wastewater supplemented with 5 mM NaNO₃ with maximal biomass productivity. A dramatic increase in lipid yield was achieved with the post-chlorinated wastewater supplemented with 25 mM NaNO₃. Low dosages of free chlorine were found to enhance microalgal growth. These findings serve as a basis for further scale-up trials using municipal wastewater as a medium for microalgal biomass and lipid production.     

Synthesis of functionalized diaryl alkanes from azines using Lewis acidic ionic liquids

Novel Lewis acidic ionic liquids containing thionyl cations and chlorozincate anions were obtained by one pot synthesis for the first time. This ionic liquid is used as catalyst for Friedel–Crafts alkylation of benzalazines and acetophenone azines for the synthesis of substituted diaryl alkanes. The products were characterized by elemental and spectral (FT-IR, 1H-NMR and 13C-NMR) analyses.     

Spectrally broadened excitonic absorption and enhanced optical nonlinearities in Dy<Superscript>3+</Superscript>-doped ZnO nanoparticles

We have synthesized Dy³⁺-doped ZnO nanoparticles at room temperature through the sol–gel method. X-ray diffraction and Scanning electron microscopic studies confirm the crystalline nature of the particles. Excitonic absorption of ZnO shows three different bands, and we observe that incorporation of Dy³⁺ results in the shifting and broadening of the n=1 absorption band of ZnO. Photoluminescence studies done at the excitation wavelength of 335 nm show broad emission containing five different bands. Open-aperture z-scan studies done at 532 nm using 5 ns laser pulses show an optical limiting behavior, which numerically fits to a three-photon type absorption process. The nonlinearity is essentially resonant, as it is found to increase consistently with Dy³⁺ concentration. This feature makes Dy³⁺-doped ZnO a flexible optical limiter for potential device applications.     

Catalyst activity comparison of alcohols over zeolites

Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 (SiO₂/Al₂O₃ = 30) catalyst was studied at 360 °C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and 1-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.     

Graphene Oxide/Carbon Nanotube Composite Hydrogels—Versatile Materials for Microbial Fuel Cell Applications

Carbonaceous nanocomposite hydrogels are prepared with an aid of a suspension polymerization method and are used as anodes in microbial fuel cells (MFCs). (Poly N‐Isopropylacrylamide) (PNIPAM) hydrogels filled with electrically conductive carbonaceous nanomaterials exhibit significantly higher MFC efficiencies than the unfilled hydrogel. The observed morphological images clearly show the homogeneous dispersion of carbon nanotubes (CNTs) and graphene oxide (GO) in the PNIPAM matrix. The complex formation of CNTs and GO with NIPAM is evidenced from the structural characterizations. The effectual MFC performances are influenced by combining the materials of interest (GO and CNTs) and are attributed to the high surface area, number of active sites, and improved electron‐transfer processes. The obtained higher MFC efficiencies associated with an excellent durability of the prepared hydrogels open up new possibilities for MFC anode applications.

     

Investigation on (EC/DMC)(70−x)wt% to LiBETI(x)wt% impact on PVdF-co-HFP/octadecylamine-MMT(montmorillonite) nano clay composite electrolytes

The composition dependence of plasticizer (ethylenecarbonate(EC)/dimethyl carbonate(DMC))_(70?x)wt% to Lithium bis(perfluoroethanesulfonyl)imide(LIBETI)_(x)wt% salt (where x?=?1.5, 3.0, 4.5, 6.0 wt%) on PVdF-co-HFP (25 wt%)/surface modified octadecylamine containing montmorrillonite (ODA-MMT) nano clay (5 wt%) matrix has been investigated by AC impedance, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and dielectric and cyclic voltammetry studies. The enhanced conductivity 2.1?×?10^?5 Scm^?1 is noted in salt rich phase (EC/DMC)_(70–6)wt% /LiBETI_(x=6)wt% (VK4). In XRD, 2θ at 20.9° confirms β-phase. In FTIR studies, vibrational bands 838, 522 and 611 cm^?1 confirm β-phase of PVdF due to clay intercalation. In DSC studies, the melting of α-phase crystallites is noted between 140–150 °C. In SEM studies, one of the membranes presents fern leaf texture confirming swelling of clay. The increase in dielectric constant and dielectric loss with decrease in frequency is attributed to high contribution of charge accumulation at the electrode–electrolyte interface. In cyclic voltammetry studies, salt-rich phase membrane (VK4) shows good cyclability than other membranes.     

Metal-Free,One-Pot,Rapid Synthesis of Tetrahydropyridines Using Acetic Acid as Solvent and Catalyst at Room Temperature

Acetic acid–promoted, one-pot synthesis of tetrahydropyridines has been developed under metal-catalyst-free conditions via a tandem reaction. High atom economy, good yield, simple procedure, no expensive column chromatography, shorter reaction time, and metal-free and mild reaction conditions are some of the important features of this protocol. The current methodology provides an alternative approach for not only highly substituted tetrahydropyridines (THPs) but also fully substituted tetrahydropyridines (FTHPs) in moderate to good yields. The plausible mechanism for the formation of THPs was greatly promoted by the H⁺ ion coming from acetic acid.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

Structures, energetics, vibrational spectra of NH4+ (H2O)(n=4,6) clusters: Ab initio calculations and first principles molecular dynamics simulations

Important structural isomers of NH(4) (+)(H(2)O)(n=4,6) have been studied by using density functional theory, Moller-Plesset second order perturbation theory, and coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)]. The zero-point energy (ZPE) correction to the complete basis set limit of the CCSD(T) binding energies and free energies is necessary to identify the low energy structures for NH(4) (+)(H(2)O)(n=4,6) because otherwise wrong structures could be assigned for the most probable structures. For NH(4) (+)(H(2)O)(6), the cage-type structure, which is more stable than the previously reported open structure before the ZPE correction, turns out to be less stable after the ZPE correction. In first principles Car-Parrinello molecular dynamics simulations around 100 K, the combined power spectrum of three lowest energy isomers of NH(4) (+)(H(2)O)(4) and two lowest energy isomers of NH(4) (+)(H(2)O)(6) explains each experimental IR spectrum.     

FT-IR, FT-Raman spectra and quantum chemical calculations of some chloro substituted phenoxy acetic acids

In this work, we will report a combined experimental and theoretical study on molecular and vibrational structure of o-chlorophenoxy acetic acid (OCPAA) and p-chlorophenoxy acetic acids (PCPAA). The FT-IR and Fourier transform-Raman spectra of both the compounds was recorded in the solid phase. The optimized geometry was calculated by HF and B3LYP methods with 6-311++G(d,p) basis set and harmonic vibrational frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-311++G(d,p) basis set. The scaled theoretical wavenumbers showed very good agreement with the experimental values. The thermodynamic functions of the title compounds were also performed at B3LYP/6-311++G(d,p) level of theory. A detailed interpretation of the infrared and Raman spectra of o-chloro and p-chlorophenoxy acetic acid is reported. The theoretical FT-IR spectrograms for the title molecules have been constructed.     

Conjugation of siRNA with Comb‐Type PEG Enhances Serum Stability and Gene Silencing Efficiency

A thiol‐modified siRNA targeting the enhanced green fluorescence protein (eGFP) gene was conjugated with RAFT‐synthesized, pyridyl disulfide‐functional poly(PEG methyl ether acrylate)s (p(PEGA)s). siRNA‐p(PEGA) conjugates demonstrated significantly enhanced in vitro serum stability and nuclease resistance compared to the unmodified and thiol‐modified siRNA. The complexes of siRNA‐p(PEGA) conjugates with a fusogenic peptide, KALA ((+)/(–) = 2) inhibited the protein expression approximately 28‐fold more than the KALA complex of the unmodified siRNA. The protein inhibition caused by siRNA‐p(PEGA)‐KALA complexes (56 ± 5%–58 ± 3% of the fluorescence expressed in non‐treated cells) was comparable to the effect of the unmodified siRNA‐lipofectamine complex (77 ± 7%).