Synthesis And Comparison Of Liquid Crystal Polymers And Monomers Containing Azobenzene Mesogens

Abstract: The syntheses of novel liquid crystal polymers containing azobenzene moieties were carried out according to convenient route having a acrylate backbone. The azobenzenes are key intermediates of the monomers and the side-chain liquid crystal polymer is the poly [α-{4-[(4-acetylphenyl)diazenyl]phenoxy}alkyloxy]acrylate in which spacer length is varied from 3 to 11 methylene units. The precursors and monomers were characterized by using FT-IR, NMR techniques. The polymers were obtained by conventional free radical polymerization using AIBN as an initiator. The thermal properties of the polymers were studied by using differential scanning calorimetry. The thermal behavior of the polymers are compared with those of the analogous monomers, the α-{4-[(4-acetylphenyl)diazenyl]phenoxy}alkyloxy acrylate and it was found that all polymers exhibited namatic phase near isotropic point and no phase transition observed in the monomers. Abstrak: Polimer hablur cecair kumpulan azobenzena telah disintesis dengan cara yang rengkas dimana akrilat telah digunakan sebagai rangka utama. Azobenzena poli[α-{4-[(4-asetilfenil) diazenil]fenoksi}alkiloksi]akrilat merupakan bahantara utama daripada monomer dan merupakan rantai sisi kepada polimer cecair hablur tersebut dengan panjang kumpulan peruang antara 3 ke 11 unit metilena. Precursor dan monomer telah dicirikan menggunakan teknik FTIR dan NMR. Polimer telah dihasilkan secara pempolimeran radikal bebas konvensional menggunakan bahan pemula AIBN. Sifat terma polimer telah dikaji menggunakan kalorimetri pengimbas pembezaan. Sifat terma polimer telah dibandingkan dengan analog monomer α-{4-[(4-asetilfenil) diazenil]fenoksi}alkiloksi akrilat, dan didapati semua polimer menunjukkan fasa namatik pada titik isotropik tetapi tiada transisi fasa dilihat berlaku pada monomer

Alcoholysis of palm oil mid-fraction by lipase from Rhizopus rhizopodiformis

A mycelial lipase from Rhizopus rhizopodiformis was prepared in fragment form. The lipase was examined to catalyze the alcoholysis of palm oil mid-fraction (PMF) in organic solvents. High percentage conversions of PMF to alkyl esters were achieved when methanol or propanol was used as acyl acceptor. Of the two most prevalent fatty acids in PMF, palmitic acid seemed to be preferred over oleic acid in the formation of methyl and propyl esters. The optimal ratio of oil to methanol in the alcoholysis reaction is 1 to 2 moles. The lipase exhibited high alcoholysis activities in nonpolar solvents (log P>2), such as hexane, benzene, toluene, and heptane. The enzyme showed exceptionally high thermostability

SORPTION OF Cu(II) BY CHEMICALLY GRAFTED HYDROXAMIC ACID-ZEOLITE (Erapan Cu(II) oleh Zeolit Terubahsuai Dengan Asid Hidroksamik)

Abstract Sorption of Cu(II) by zeolite sorbent chemically modified with hydroxamic acid (HASiZP) is described. The maximum sorption capacity of Cu(II) occurred at pH 5. Sorption capacity of Cu(II) by HASiZP was doubled compared to the original zeolite. Kinetic study shows that Cu(II) sorption followed by second order kinetic model. The sorption of Cu(II) followed Langmuir isotherm model with maximum capacity of 33.32 mg/g at 25°C and increased to 48.12 mg/g at 70°C. Cu(II) sorption by the HASiZP was endothermic and spontaneous processes with positive values of entropy changes. Keywords: Hydroxamic acid-grafted zeolite, Cu(II), sorption. Abstrak Kertas ini membincangkan erapan Cu(II) oleh zeolit terubahsuai oleh asid hidroksamik (HASiZP). Erapan maksimum Cu(II) berlaku pada pH 5. Muatan erapan Cu(II) oleh HASiZP meningkat dua kali ganda berbanding zeolit asal. Kajian kinetik menunjukkan erapan Cu(II) mengikuti model kinetic order kedua. Erapan Cu(II) mematuhi model isotherma Langmuir dengan muatan maksimum 33.32 mg/g pada 25°C dan meningkat kepada 48.12 mg/g pada 70°C. Erapan Cu(II) oleh HASiZP adalah proses endotherma dan spontan dengan perubahan entropi positif. Kata kunci: Zeolit terubahsuai oleh asid hidroksamik, Cu(II), erapan Introduction Heavy metals are toxic substances and must be removed from wastewater prior to their discharge into receiving waters. Among methods available for heavy metal removal, sorption by ion exchange is an attractive one due to its simplicity and safe which requires only mild operating conditions. Using a low cost exchanger such as zeolite, the method can be made cost-effective. Zeolites either synthetic or natural are hydrated aluminosilicate. The structures of zeolites consist of three dimensional frameworks of SiO 4 and AlO 4 tetrahedra. The isomorphous replacement of Si 4+ by Al 3+ produces a negative charge in the lattice. The negative charge is balanced by cations such as Na + and

Application of drying model to determine extraction behaviours on peanut skin oil recovery by supercritical carbon dioxide-ethanol

The main objective of this study was to determine the mass transfer for extraction of peanut (Arachis hypogea) skin by using drying models as alternatives extraction models. The mass transfer was measured at the pressure ranging from 10 MPa to 30 MPa, temperature of 40 oC to 70 oC, and rate of modifier 0.075 mL/min to 0.225 mL/min. The Lewis, Page, Peleg, Henderson and Pabis, and Avhad and Macetti as drying models were modified to illustrate the extraction process and to transform as alternative empirical models. An average absolute relative deviation percentage (AARD%) of Lewis, Page, Peleg, Henderson - Pabis, and Avhad-Macetti was 9.52%, 4.67%, 19.41%, 0.26%, and 0.04%. Avhad and Macetti model offered the best fitting between experimental data and modelling data. The results showed that drying model was applicable to correlate the experimental data of extraction process due to low percentage of error and high coefficient determination

Corrosion behavior of friction stir welded lap joints of AA6061-T6 aluminum alloy

In this work, the corrosion behaviors of friction-stir lap welding of 6061-T6 Al-alloy are studied. The friction-stir lap welding was performed under different welding conditions (rotation speed and welding speed). The corrosion behavior of the parent alloy, the weld nugget zone (WNZ), and the heat affected zone (HAZ) of each welded sample working as an electrode, were investigated by the Tafel polarization test in 3.5 wt. (%) NaCl at ambient temperature. The morphology of the corroded surface of each region was analyzed by scanning electron microscopy together with energy dispersive spectroscopy (SEM-EDS). The results showed that the corrosion resistance of the parent alloy was better than the WNZ and the HAZ in both welding conditions. Localized pit dissolution and intergranular corrosion were the dominant corrosion types observed in the parent alloy, WNZ, and HAZ. The parent alloy, WNZ, and HAZ exhibited similar corrosion potentials (Ecorr) after T6 heat treatment. This treatment had a better effect on the corrosion resistance of the welded regions than the parent alloy

Conceptual Framework on Workplace Deviance Behavior: A Review

This article aims to highlight the importance of organizational climate with both destructive and constructive deviance behaviour in different cultural setting with workplace as a common ground. First, we discuss the need for research in workplace deviance especially destructive and constructive deviance behaviour with the review of previous studies from deviance literature. Next, we present the importance of climate and culture with both destructive and constructive deviance by proposing relationship among them with the help of a framework. The presented theoretical framework can be useful for conducting future empirical research. Finally, we present the conclusion and future research in conducting cross-national research with respect to deviance

A Mechanistic View of the Role of E3 in Sumoylation

Sumoylation, the covalent attachment of SUMO (Small Ubiquitin-Like Modifier) to proteins, differs from other Ubl (Ubiquitin-like) pathways. In sumoylation, E2 ligase Ubc9 can function without E3 enzymes, albeit with lower reaction efficiency. Here, we study the mechanism through which E3 ligase RanBP2 triggers target recognition and catalysis by E2 Ubc9. Two mechanisms were proposed for sumoylation. While in both the first step involves Ubc9 conjugation to SUMO, the subsequent sequence of events differs: in the first E2-SUMO forms a complex with the target and E3, followed by SUMO transfer to the target. In the second, Ubc9-SUMO binds to the target and facilitates SUMO transfer without E3. Using dynamic correlations obtained from explicit solvent molecular dynamic simulations we illustrate the key roles played by allostery in both mechanisms. Pre-existence of conformational states explains the experimental observations that sumoylation can occur without E3, even though at a reduced rate. Furthermore, we propose a mechanism for enhancement of sumoylation by E3. Analysis of the conformational ensembles of the complex of E2 conjugated to SUMO illustrates that the E2 enzyme is already largely pre-organized for target binding and catalysis; E3 binding shifts the equilibrium and enhances these pre-existing populations. We further observe that E3 binding regulates allosterically the key residues in E2, Ubc9 Asp100/Lys101 E2, for the target recognition

Crystal Structure of UBA2ufd-Ubc9: Insights into E1-E2 Interactions in Sumo Pathways

Canonical ubiquitin-like proteins (UBLs) such as ubiquitin, Sumo, NEDD8, and ISG15 are ligated to targets by E1-E2-E3 multienzyme cascades. The Sumo cascade, conserved among all eukaryotes, regulates numerous biological processes including protein localization, transcription, DNA replication, and mitosis. Sumo conjugation is initiated by the heterodimeric Aos1-Uba2 E1 enzyme (in humans called Sae1-Uba2), which activates Sumo's C-terminus, binds the dedicated E2 enzyme Ubc9, and promotes Sumo C-terminal transfer between the Uba2 and Ubc9 catalytic cysteines. To gain insights into details of E1-E2 interactions in the Sumo pathway, we determined crystal structures of the C-terminal ubiquitin fold domain (ufd) from yeast Uba2 (Uba2ufd), alone and in complex with Ubc9. The overall structures of both yeast Uba2ufd and Ubc9 superimpose well on their individual human counterparts, suggesting conservation of fundamental features of Sumo conjugation. Docking the Uba2ufd-Ubc9 and prior full-length human Uba2 structures allows generation of models for steps in Sumo transfer from Uba2 to Ubc9, and supports the notion that Uba2 undergoes remarkable conformational changes during the reaction. Comparisons to previous structures from the NEDD8 cascade demonstrate that UBL cascades generally utilize some parallel E1-E2 interaction surfaces. In addition, the structure of the Uba2ufd-Ubc9 complex reveals interactions unique to Sumo E1 and E2. Comparison with a previous Ubc9-E3 complex structure demonstrates overlap between Uba2 and E3 binding sites on Ubc9, indicating that loading with Sumo and E3-catalyzed transfer to substrates are strictly separate steps. The results suggest mechanisms establishing specificity and order in Sumo conjugation cascades

Cognitive effects of transcranial direct current stimulation combined with working memory training in fibromyalgia: a randomized clinical trial

Cognitive dysfunction in fibromyalgia has been reported, especially memory. Anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex (DLPFC) has been effective in enhancing this function. We tested the effects of eight sessions of tDCS and cognitive training on immediate and delayed memory, verbal fluency and working memory and its association with brain-derived neurotrophic factor (BDNF) levels. Forty females with fibromyalgia were randomized to receive eight sessions of active or sham tDCS. Anodal stimulation (2 mA) was applied over the DLPFC and online combined with a working memory training (WMT) for 20 minutes. Pre and post-treatment neurocognitive tests were administered. Data analysis on deltas considering years of education and BDNF as covariates, indicated active-tDCS + WMT significantly increased immediate memory indexed by Rey Auditory Verbal Learning Test score when compared to sham. This effect was dependent on basal BDNF levels. In addition, the model showed active stimulation increased orthographic and semantic verbal fluency scores (Controlled Oral Word Association Test) and short-term memory (Forward Digit Span). The combination of both techniques seemed to produce effects on specific cognitive functions related to short-term and long-term episodic memory and executive functions, which has clinical relevance for top-down treatment approaches in FM.financiamento: This research was supported by grants and material support from the following Brazilian agencies: Committee for the Development of Higher Education Personnel - CAPES - PNPD/CAPES and material support. National Council for Scientific and Technological Development - CNPq (grants to Dr. I.L.S. Torres, Dr. W. Caumo). Postgraduate Program in Medical Sciences at the School of Medicine of the Federal University of Rio Grande do Sul (material support). Postgraduate Research Group at the Hospital de Clinicas de Porto Alegre - FIPE HCPA (material support). Foundations for Support of Research at Rio Grande do Sul (FAPERGS) (material support)