Enterobacter cloacae is a highly pathogenic Gram-negative proteobacterium which is responsible for a wide array of infections. In the present study, the fermentation culture of E. cloacae has yielded one new oxolane compound, Rimboxo (1) in addition to three known compounds, i.e. Maculosine (2), phenylacetic acid (3) and methyl myristate (4). These compounds were isolated and characterised using extensive chromatographic and spectroscopic methods, and were subjected to cytotoxicity evaluations.
A flexible solid polymer electrolyte (SPE) system based on poly(ε-caprolactone) (PCL), a FDA approved non-toxic and biodegradable material in the effort to lower environmental impact was prepared. Ammonium thiocyanate (NH4SCN) and ethylene carbonate (EC) were incorporated as the source of charge carriers and plasticizing agent, respectively. When 50wt.% of ethylene carbonate (EC) was added to PCL-NH4SCN system, the conductivity increased by two orders from of 3.94×10(-7)Scm(-1) to 3.82×10(-5)Scm(-1). Molecular vibrational analysis via infrared spectroscopy had been carried out to study the interaction between EC, PCL and NH4SCN. The relative percentage of free ions, ion pairs and ion aggregates was calculated quantitatively by deconvoluting the SCN(-) stretching mode (2030-2090cm(-1)). This study provides fundamental insight on how EC influences the free ion dissociation rate and ion mobility. The findings are also in good agreement to conductivity, differential scanning calorimetry and X-ray diffraction results. High dielectric constant value (89.8) of EC had made it an effective ion dissociation agent to dissociate both ion pairs and ion aggregates, thus contributing to higher number density of free ions. The incorporation of EC had made the polymer chains more flexible in expanding amorphous domain. This will facilitate the coupling synergy between ionic motion and polymer segmental motion. Possible new pathway through EC-NH4(+) complex sites for ions to migrate with shorter distance has been anticipated. This implies an easier ion migration route from one complex site to another.
Magnesium-based polymer gel electrolytes consist of magnesium triflate (MgTf) salt, a mixture of ethylene carbonate (EC) and diethyl carbonate (DEC) solvents as well as cellulose acetate as a polymeric agent were prepared via direct dissolution method. The highest ionic conductivity obtained for MgTf-EC:DEC(1:1) liquid electrolytes was 2.66 x 10-3 S cm-1 and enhanced to 2.73 x 10-3 S cm-1 with the addition of cellulose acetate. These results were in agreement with the activation energy obtained with the lowest value of 0.11. The best explanation on the enhancement in ionic conductivity of PGE is due to the “breathing polymeric chain model”. The plots of conductivity-temperature shown to obey an Arrhenius rule. The electrical properties of the sample with the highest conductivity were analyzed using electrical permittivity-based frequency and temperature dependence in the range of 100 Hz - 1 MHz and 303-373K, respectively. The variation in dielectric permittivity (εr and εi) as a function of frequency at different temperatures exhibited decays at higher frequencies and a dispersive behavior at low frequencies. Based on the observed electrical properties, it can be inferred that this polymer gel electrolyte could be a promising candidate as an electrolyte in electrochemical devices.
Solid polymer electrolyte based on methyl cellulose (MC)-lithium triflate (LiCF3SO3) plasticised with ethylene carbonate (EC) was prepared using solution cast technique. The X-ray diffraction (XRD) studies proved that the amorphous nature of the electrolyte systems was increases due to the addition of salt and plasticiser. The improved surface morphology of plasticised polymer system ensures it has good electrode-electrolyte contact during performance testing. The polymer electrolyte was found to have high thermal stability indicating that the electrolyte can be used at higher temperature. The ionic conductivity increased up to 1.24 x 10-4 S cm-1 at optimum amount of EC plasticiser associated to the effect of plasticiser that initially leads to the formation of Li+-EC complex. Consequently, it reduces the fraction of polymer-Li+ complex which contributes to the increase of the segmental chain flexibility in the plasticized system. Temperature dependent studies indicate ionic conductivity increase due to the temperature increase and is in line with Arrhenius behaviour pattern. An activation energy of 0.26 eV at highest conductivity sample was obtained. The addition of plasticiser lowers the activation energy thus increasing the ion mobility of the system and contributing to ionic conductivity increment. The plasticization method is a promising means to dealing with the solid polymer electrolyte problem and producing electrolytes that meet the needs of electrochemical devices.
The effects of osmotic dehydration (OD) treatment on volatile compound (myristicin) content and the antioxidant capacity of nutmeg (Myristica fragrans) were studied. Fresh nutmeg pericarps were treated with varying sugar concentrations (60, 70, 80%) with different soaking periods at ambient temperature. The OD-treated nutmeg extracts were analyzed for myristicin content via Gas Chromatography Flame Ionization Detector. The phenolic content and antioxidant capacity were analyzed using Follin-Ciocalteu and a free radical scavenging activity assay. The myristicin content was highest (1.69 mg/100 mg) at 80% sugar concentration after 3 h of soaking. Total phenolic content and free radical scavenging activity were highest at 3 h of 80% sugar solution treatment with values of 76.90% and 1.75 mg GAE/g, respectively. OD treatment at varying sugar concentration levels and durations affects the production of myristicin and antioxidant composition. Treatment of nutmeg with OD at 80% sugar concentration for 3 h is preferable, resulting in an acceptable level of myristicin and high antioxidants.
The polymer electrolytes composing of the blend of polyvinyl chloride-polymethyl methacrylate (PVC/PMMA) with lithium triflate (LiCF3SO3) as salt, ethylene carbonate (EC) and dibutyl phthalate (DBP) as plasticizers and silica (SiO2) as the composite filler were prepared. FTIR studies confirm the complexation between PVC/PMMA blends. The CCl stretching mode at 834 cm-1 for pure PVC is shifted to 847 cm-1 in PVC-PMMA-LiCF3SO3 system. This suggests that there is interaction between Cl in PVC with Li+ ion from LiCF3SO3. The band due to OCH3 at 1150 cm-1 for PVC-PMMA blend is shifted to 1168 cm-1 in PVC-PMMA-LiCF3SO3 system. This shift is expected to be due to the interaction between Li+ ion and the oxygen atom in PMMA. The symmetric vibration band and the asymmetric vibration band of LiCF3SO3 at 1033 and 1256 cm-1 shifted to 1075 and 1286 cm-1 in the DBP-EC plasticized PVC-PMMA-LiCF3SO3 complexes. The interaction between Li+ ions and SiO2 will lead to an increase in the number of free plasticizers (which does not interact with Li+ ions). When the silica content increases from 2% to 5%, the intensity of the peak at 896 cm-1 (due to the ring breathing vibration of free EC) increases in PVC-PMMA-LiCF3SO3-DBP-EC system.
Hexane, dichloromethane and methanol extracts of the roots of Piper sarmentosum Roxb. were screened for toxicity towards Sitophilus oryzae (L.), Rhyzopertha dominica (F.), and Plodia interpunctella (Hübner) and the hexane extract exhibited the highest mortality percentage. Bioassay-guided fractionation of the hexane extract resulted in the isolation of asaricin 1, isoasarone 2, and trans-asarone 3. Asaricin 1 and isoasarone 2 were the most toxic compounds to Sitophilus oryzae, Rhyzopertha dominica, and Plodia interpunctella. Sitophilus oryzae and Rhyzopertha dominica exposed to asaricin 1 and isoasarone 2 required the lowest median lethal time. Insecticidal activity of trans-asarone 3 showed consistent toxicity throughout the 60 days towards all three insects as compared to asaricin 1 and isoasarone 2. Asaricin 1 and isoasarone 2 at different doses significantly reduced oviposition and adult emergence of the three insects in treated rice. Trans-asarone 3 had lowest toxicity with highest LC and LT values in all tested insects relative to its mild oviposition inhibition and progeny activity. Moreover, asaricin 1 and isoasarone 2 significantly inhibited acetylcholinesterase in comparison with trans-asarone 3 and the control. Acetylcholinesterase inhibition of Rhyzopertha dominica and Plodia interpunctella by asaricin 1 and isoasarone 2 were lower than that of Sitophilus oryzae, which correlated with their higher resistance.
Gel polymer electrolytes using imidazolium based ionic liquids have attracted much attention in dye-sensitized solar cell applications. Hydroxypropyl cellulose (HPC), sodium iodide (NaI), 1-methyl-3-propylimidazolium iodide (MPII) as ionic liquid (IL), ethylene carbonate (EC) and propylene carbonate (PC) are used for preparation of non-volatile gel polymer electrolyte (GPE) system (HPC:EC:PC:NaI:MPII) for dye-sensitized solar cell (DSSC) applications. The highest ionic conductivity of 7.37 × 10(-3) S cm(-1) is achieved after introducing 100% of MPII with respect to the weight of HPC. Temperature-dependent ionic conductivity of gel polymer electrolytes is studied in this work. XRD patterns of gel polymer electrolytes are studied to confirm complexation between HPC polymer, NaI and MPII. Thermal behavior of the GPEs is studied using simultaneous thermal analyzer (STA) and differential scanning calorimetry (DSC). DSSCs are fabricated using gel polymer electrolytes and J-V centeracteristics of fabricated dye sensitized solar cells were analyzed. The gel polymer electrolyte with 100 wt.% of MPII ionic liquid shows the best performance and energy conversion efficiency of 5.79%, with short-circuit current density, open-circuit voltage and fill factor of 13.73 mA cm(-2), 610 mV and 69.1%, respectively.
Ethylene glycol is a super commodity chemical and it has vital roles in various applications. Its co-production with other chemicals, such as ethylene carbonate and glycerol carbonate, has promised cheaper production cost. Its quantification presents a challenge as its contaminants, such as ethylene carbonate, produce a signal-reducing effect in flame ionized detector. The aim of this study is to evaluate external standard to quantify the composition of glycol mixture. Measurement system analysis was employed on the external standard method. Reliability of the external standard is statistically significant with low p-values, excellent capability indices, and high F-values. The external standard is found to have remarkable precision and trueness as both capability indices are mirroring each other. Furthermore, the capability analysis has a strong correlation with quality measurement. Based on capability indices, the limit of detection is recommended at S/N = 25 and the limit of quantification is recommended at S/N = 100 for a reliable measurement. A high degree of reliability is achieved coherently as almost all uncertainties of coefficients of variations are less than 5%. The established method was validated and successfully applied to glycol mixture at azeotropic distillation pilot plant.
In this study polymer electrolytes composed of poly(methyl methacrylate) (PMMA) as a host polymer and ethylene carbonate (EC) as a plasticizer complexed with different lithium salts, i.e. lithium tetrafluoroborate (LiBF4) and lithium triflate (LiCF3SO3) were prepared by the solution casting technique. The conductivities of the films were characterized by impedance spectroscopy. At room temperature, the highest conductivities were 4.07 × 10–7S cm–1 and 3.40 × 10–5 S cm–1 achieved, respectively from the films containing 30 wt% LiBF4 in the PMMA-EC-LiBF4 system and 35 wt% LiCF3SO3 in the PMMA-EC-LiCF3SO3 system. The conductivity-temperature dependence of the films seemed to obey the Arrhenius equation in which the ion transport in these materials was thermally assisted. Scanning electron microscopy analysis showed that the surface of PMMA-EC-LiCF3SO3 film was smooth and homogeneous, hence lithium ions could traverse through the PMMA-EC-LiCF3SO3 film more easily compared to the PMMA-EC-LiBF4 film. X-Ray diffraction studies revealed that complexation had occurred and the complexes formed were amorphous.
Polymer electrolytes based on polyacrylonitrile (PAN) containing inorganic salts; lithium triflate (LiCF3SO3) and sodium triflate (NaCF3SO3) and ethylene carbonate (EC) as plasticizer were prepared using solvent casting technique. In this study, five systems of plasticized and unplasticized polymer electrolyte films i.e. PAN-EC, PAN-LiCF3SO3, PAN-NaCF3SO3 PAN-EC-LiCF3SO3 and PAN-EC-NaCF3SO3 systems have been prepared. The structural and morphological properties of the films were studied using infrared spectroscopy and scanning electron microscopy (SEM) while the conductivity study was done by using impedance spectroscopy. The infrared results revealed that interaction had taken place between the nitrogen atoms of PAN and Li+ and Na+ ions from the salts. SEM micrographs showed that the plasticized film, PAN-EC-NaCF3SO3 has bigger pores than PAN-EC-LiCF3SO3 film resulting in the film containing NaCF3SO3 salt being more conductive. On addition of salts and plasticizer, the conductivity of pure PAN increases to three orders of magnitude. The plasticized film containing NaCF3SO3 salt has a higher conductivity compared to that containing LiCF3SO3 salt. This result showed that the interaction between Li+-ion and the nitrogen atom of PAN was stronger than that of Na+-ion. The conductivity-temperature dependence of the highest conducting film from each system follows Arrhenius equation in the temperature range of 303 to 353 K. The conductivity-pressure study in the range of 0.01 - 0.09 MPa showed that the conductivity decreased when pressure was increased. This can be explained in term of free volume model.
A binary salt system utilizing lithium iodide (LiI) as the auxiliary component has been introduced to the N-phthaloylchitosan (PhCh) based gel polymer electrolyte consisting of ethylene carbonate (EC), dimethylformamide (DMF), tetrapropylammonium iodide (TPAI), and iodine (I2) in order to improve the performance of dye-sensitized solar cell (DSSC) with efficiency of 6.36%, photocurrent density, JSC of 17.29mAcm-2, open circuit voltage, VOC of 0.59V and fill factor, FF of 0.62. This efficiency value is an improvement from the 5.00% performance obtained by the DSSC consisting of only TPAI single salt system. The presence of the LiI in addition to the TPAI improves the charge injection rates and increases the iodide contribution to the total conductivity and both factors contribute to the increase in efficiency of the DSSC. The interaction behavior between polymer-plasticizer-salt was thoroughly investigated using EIS, FTIR spectroscopy and XRD.
Fourier transform infrared (FT-IR) spectroscopic studies have been undertaken to investigate the interactions among components in a system of hexanoyl chitosan-lithium trifluoromethanesulfonate (LiCF(3)SO(3))-diethyl carbonate (DEC)/ethylene carbonate (EC). LiCF(3)SO(3) interacts with the hexanoyl chitosan to form a hexanoyl chitosan-salt complex that results in the shifting of the N(COR)(2), CONHR and OCOR bands to lower wavenumbers. Interactions between EC and DEC with LiCF(3)SO(3) has been noted and discussed. Evidence of interaction between EC and DEC has been obtained experimentally. Studies on polymer-plasticizer spectra suggested that there is no interaction between the polymer host and plasticizers. Competition between plasticizer and polymer on associating with Li(+) ions was observed from the spectral data for gel polymer electrolytes. The obtained spectroscopic data has been correlated with the conductivity performance of hexanoyl chitosan-based polymer electrolytes.