Structural,electrochemical, and adsorption studies of Ni and Zn benzylimidazole coordination polymers with terephthalate linkers

Two coordination polymers, [Ni(bim)₂(L1)(H₂O)₂] _n (CP-1) and [Zn(bim)(L1)(Cl)] _n (CP-2) (bim = 1-benzylimidazole, L1 = terephthalic acid), were synthesized and characterized by physicochemical and spectroscopic methods. The Ni(II) center in CP-1 is octahedral, while the Zn(II) center in CP-2 is tetrahedral. CP-1 and CP-2 were used to modify carbon paste electrodes to assess their effect on the electrochemical behavior of ferricyanide. The redox reactions of ferricyanide on both electrodes proved to be reversible and diffusion controlled, with ferricyanide diffusion coefficients for CP-1 and CP-2 of 1.88 × 10⁵ and 3.44 × 10⁵ cm² s^?1, respectively. These coordination polymers were also investigated for their adsorption behavior toward two dyes: Chicago sky blue and methylene blue. CP-1 and CP-2 both rapidly adsorbed the anionic Chicago sky blue dye by different intermolecular interactions; in contrast, the cationic methylene blue dye was adsorbed to a lesser extent. The adsorption of these CPs depends on the charge but not the size of the dye. Addition of methanolic potassium nitrate solution caused the release of the adsorbed dyes.     

Enhanced Bioethanol Production from Potato Peel Waste Via Consolidated Bioprocessing with Statistically Optimized Medium

In this study, an extensive screening was undertaken to isolate some amylolytic microorganisms capable of producing bioethanol from starchy biomass through Consolidated Bioprocessing (CBP). A total of 28 amylolytic microorganisms were isolated, from which 5 isolates were selected based on high α-amylase and glucoamylase activities and identified as Candida wangnamkhiaoensis, Hyphopichia pseudoburtonii (2 isolates), Wickerhamia sp., and Streptomyces drozdowiczii based on 26S rDNA and 16S rDNA sequencing. Wickerhamia sp. showed the highest ethanol production (30.4 g/L) with fermentation yield of 0.3 g ethanol/g starch. Then, a low cost starchy waste, potato peel waste (PPW) was used as a carbon source to produce ethanol by Wickerhamia sp. Finally, in order to obtain maximum ethanol production from PPW, a fermentation medium was statistically designed. The effect of various medium ingredients was evaluated initially by Plackett-Burman design (PBD), where malt extracts, tryptone, and KH₂PO₄ showed significantly positive effect (p value < 0.05). Using Response Surface Modeling (RSM), 40 g/L (dry basis) PPW and 25 g/L malt extract were found optimum and yielded 21.7 g/L ethanol. This study strongly suggests Wickerhamia sp. as a promising candidate for bioethanol production from starchy biomass, in particular, PPW through CBP.     

Citronellal cyclisation over heteropoly acid supported on modified montmorillonite catalyst: effects of acidity and pore structure on catalytic activity

Citronellal cyclisation to isopulegol is an important intermediate step in the production of menthol. Several heteropoly acids (PTA) supported on modified montmorillonite (MM) catalysts were synthesized and then tested in cyclisation reactions. The prepared samples were characterized by XRD, ICP-OES, FTIR, N₂ sorption, NH₃-TPD, pyridine adsorption, amine titration and FE-SEM techniques. Effects of post-treatment were studied on montmorillonite pore structure, acidity and catalytic activity. The catalytic activity and isopulegol selectivity improved with acid-treatment and PTA loading. The amount of Lewis acidity of montmorillonite was enhanced with acid-treatment and PTA impregnation. In cyclisation, highest catalytic activity (31.87 mmol cat g^?1 min^?1) was achieved with 96% isopulegol yield in the use of 20% PTA-MM catalyst. The highest catalytic activity and selectivity were obtained in the presence of higher acidity and strong Lewis acidic sites, whereas effects of pore structure blockage seemed minor. The catalytic activity further decreased with the loss of active acidic sites (L and B) due to PTA decomposition with calcination at a higher temperature.     

Inequalities for the derivative of a polynomial

Let P(z) be a polynomial of degreen which does not vanish in ¦z¦ <k, wherek > 0. Fork ≤ 1, it is known that

$$\mathop {\max }\limits_{|z| = 1} |P'(z)| \leqslant \frac{n}{{1 + k^n }}\mathop {\max }\limits_{|z| = 1} |P(z)|$$

, provided ¦P’(z)¦ and ¦Q’(z)¦ become maximum at the same point on ¦z¦ = 1, where\(Q(z) = z^n \overline {P(1/\bar z)} \). In this paper we obtain certain refinements of this result. We also present a refinement of a generalization of the theorem of Tu?an.

     

The true nature of a complex of 1,10-phenanthroline with the ammonium ion; crystal structure of bis-phenanthrolineprotium perchlorate

Herzog's reported bis-1,10-phenanthrolineammonium perchlorate, [(phen)₂(NH₄)](ClO₄) is in fact the known 2:1 adduct of l,10-phenanthroline (phen) with perchloric acid, [(phen)₂H](CIO₄). Its crystal structure, mode of formation, and properties are described. The compound crystallizes in the triclinic space group with , a = 7.2510(8), b = 13.120(2), c = 22.083(12) Å, = 77.4550(12), = 84.45(2), = 82.204(14)°, V = 2026.7(6) ų, Z = 4, and D _c = 1.510 g cm^–3. It contains cationic columns of alternating 1,10-phenanthroline and its conjugate acid.     

A hybrid defocused region segmentation approach using image matting

Multidimensional Systems and Signal Processing - In this paper, a hybrid defocused region segmentation using image matting is proposed. The technique incorporates three sharpness metrics which are...     

Efficient Shadow Encoding Scheme Towards Power Spectrum Density in Digital Network Communication

Wireless Personal Communications - Digital communication based on the conversion of data which only possible through digital conversion techniques. From the last couple of years, many digital...     

Training size optimization with reduced complexity in cell-free massive MIMO system

Training sequence is used in multiple antenna systems to estimate channel state information and mitigate channel distortion between transmitter and receiver. However, the training sequence or pilot must be limited to a certain size in order to reduce the impact of overhead loss due to limited channel coherence length in mobile users. In this paper, we proposed to use training size optimization in cell-free massive MIMO system. In addition, we proposed and compared the performance of different training size optimization algorithms, namely exhaustive search optimization, bisection optimization and min–max optimization, with each method has different level of calculation complexities. The results showed that in general, all of the 3 training length optimization methods improved the downlink rate compared to the conventional pilot length method. We also showed that the training optimization methods are more effective when the coherence length is small or the number of users is very large. In the case of large number of users or small coherence length, the exhaustive search has the best median downlink rate, followed closely by min–max optimum and finally the bisection method. Even though the exhaustive search optimization has the best downlink rate, we showed that the proposed reduce optimization complexity methods has significantly less calculation complexity. In addition, the median downlink rate performance of min–max optimization method is only slightly less than that of the exhaustive search method for various number of users and coherence length.

     

Properties and structural characterization of a complex salt, 2[C12H18N4OS]·[Sb2Cl10], obtained by the reaction of thiamine (vitamin B1) with antimony trichloride

Thiamine hydrochloride (vitamin B₁) reacts with antimony trichloride in methanol to produce a crystalline compound which has been characterized as the salt 2[C₁₂H₁₈N₄OS]·[Sb₂Cl₁₀] by X-ray crystallography. The compound crystallizes in the triclinic space group ,b=11.029(2),c=12.234(2) Å, =108.75(2), =102.67(2), =103.59(2)°,U=1041.52 ų,D _c=1.80 g cm^–3,Z=1. The crystal structure consists of discrete [C₁₂H₁₈N₄OS]²⁺ cations and chloro bridged [Cl₄Sb(-Cl)₂SbCl₄]^4- anions in 2:1 ratio, held together by hydrogen bonds and electrostatic forces.     

Reactions of [Mn2(μ-pyS)2(CO)6] (pySH=pyridine-2-thiol) with triphenylphosphine (PPh3), diphenylphosphine (PHPh2) and bis(diphenylphosphino)methane (dppm): X-ray crystal structure of [Mn(pyS)(η1-dppm)2(CO)2]

The dimeric complex [Mn₂(-pyS)₂(CO)₆] (1) reacted with 2 M equivalents of both PPh₃ and PHPh₂ to give the respective monomeric phosphine complexes [Mn(pyS)(L)(CO)₃][L = PPh₃ (2) and PHPh₂ (3)]; with 4 M equivalents of dppm, it yielded the complex [Mn(pyS)(¹-dppm)₂(CO)₂](4). An X-ray structure determination of 4 shows that it crystallizes in the monoclinic space group P2₁/n with a = 11.027(3), b = 24.984(7), c = 18.379(5) Å, = 99.870(8)°, V = 4988(2) ų, and Z = 4. The complex has an octahedral geometry with the chelating pyS ligand and two CO groups occupying the equatorial sites and the two monodentate dppm ligands lying in the trans positions.