Flocculation phenomenon of a mutant flocculent Saccharomyces cerevisiae strain: Effects of metal ions, sugars, temperature, pH, protein-denaturants and enzyme treatments

The flocculation mechanism of a stable mutant flocculent yeast strain Saccharomyces cerevisiae KRM-1 was quantitatively investigated for potential industrial interest. It was found that the mutant flocculent strain was NewFlo phenotype by means of sugar inhibition test. The flocculation was completely inhibited by treatment with proteinase K, protein-denaturants and carbohydrate modifier. The absence of calcium ions significantly inhibited the flocculation, indicating that Ca2+ was specifically required for flocculation. The flocculation was stable when temperature below 70°C and pH was in the range of 3.0 - 6.0. The flocculation onset of the mutant flocculent strain was in the early stationary growth phase, which coincided with glucose depletion in the batch fermentation for the production of ethanol from kitchen refuse medium. The results are expected to help develop better strategies for the control of mutant flocculent yeast for future large-scale industrial ethanol fermentation

Orbital Degeneracy and Peierls Instability in Triangular Lattice Superconductor Ir1−x_{1-x}Ptx_xTe2_2

We have studied electronic structure of triangular lattice Ir$_{1-x}$Pt$_x$Te$_2$ superconductor using photoemission spectroscopy and model calculations. Ir $4f$ core-level photoemission spectra show that Ir $5d$ $t_{2g}$ charge modulation established in the low temperature phase of IrTe$_2$ is suppressed by Pt doping. This observation indicates that the suppression of charge modulation is related to the emergence of superconductivity. Valence-band photoemission spectra of IrTe$_2$ suggest that the Ir $5d$ charge modulation is accompanied by Ir $5d$ orbital reconstruction. Based on the photoemission results and model calculations, we argue that the orbitally-induced Peierls effect governs the charge and orbital instability in the Ir$_{1-x}$Pt$_x$Te$_2$.Comment: 5 pages,4 figure

Evaluation of pressed shredded empty fruit bunch (EFB)-palm oil mill effluent (POME) anaerobic sludge based compost using Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) analysis

Pressed-shredded empty fruit bunches (EFB) and palm oil mill effluent (POME) anaerobic sludge from a 500 m3 closed anaerobic digester system was utilized for the co-composting treatment. Scanning electron microscopy (SEM) analysis showed that the shredding-pressing treatment on EFB gave better results in removing the debris and silica bodies as compared to only shredding treatment. However, similar characteristics were detected in both physically-treated EFB samples by Fourier transform infrared (FTIR) analysis, mainly in the regions of 900 to 1740 and 2800 to 3400 cm-1. After the anaerobic digestion of fresh raw POME, the protein origin (Amide I) band appeared in the POME anaerobic sludge. Besides, the band intensities at 2925 and 2855 cm-1 which attributed to the composition of fat and lipid was decreased. The maturity of the composting material after 40 days of treatment was detected by the appearance of the nitrate band at 1376 cm-1 and the results corresponded to the final C/N ratio of 12.4. Solid state 13C CP/MAS nuclear magnetic resonance (NMR) was also used to reveal the characteristic changes of pressed-shredded EFB-POME anaerobic sludge based compost.Key words: Empty fruit bunch, palm oil mill effluent, compost

Antiferromagnetic Heisenberg chains with bond alternation and quenched disorder

We consider S=1/2 antiferromagnetic Heisenberg chains with alternating bonds and quenched disorder, which represents a theoretical model of the compound CuCl_{2x}Br_{2(1-x)}(\gamma-{pic})_2. Using a numerical implementation of the strong disorder renormalization group method we study the low-energy properties of the system as a function of the concentration, x, and the type of correlations in the disorder. For perfect correlation of disorder the system is in the random dimer (Griffiths) phase having a concentration dependent dynamical exponent. For weak or vanishing disorder correlations the system is in the random singlet phase, in which the dynamical exponent is formally infinity. We discuss consequences of our results for the experimentally measured low-temperature susceptibility of CuCl_{2x}Br_{2(1-x)}(\gamma-{pic})_2

Ground State and Magnetization Process of the Mixture of Bond-Alternating and Uniform S=1/2 Antiferromagnetic Heisenberg Chains

The mixture of bond-alternating and uniform S=1/2 antiferromagnetic Heisenberg chains is investigated by the density matrix renormalization group method. The ground state magnetization curve is calculated and the exchange parameters are determined by fitting to the experimentally measured magnetization curve of \CuCl$_{2x}$Br$_{2(1-x)}$($\gamma$-pic)$_2$. The low field behavior of the magnetization curve and low temperature behavior of the magnetic susceptibility are found to be sensitive to whether the bond-alternation pattern (parity) is fixed all over the sample or randomly distributed. The both quantities are compatible with the numerical results for the random parity model.Comment: 5 pages, 7 figures. Final and enlarged version accepted for publication in J. Phys. Soc. Jp

Effects of palm oil mill effluent (POME) anaerobic sludge from 500 m3 of closed anaerobic methane digested tank on pressed-shredded empty fruit bunch (EFB) composting process

In this study, co-composting of pressed-shredded empty fruit bunches (EFB) and palm oil mill effluent (POME) anaerobic sludge from 500 m3 closed anaerobic methane digested tank was carried out. High nitrogen and nutrients content were observed in the POME anaerobic sludge. The sludge was subjected to the pressed-shredded EFB to accelerate the co-composting treatment. In the present study, changes in the physicochemical characteristics of co-composting process were recorded and evaluated. The cocomposting treatment was completed in a short time within 40 days with a final C/N ratio of 12.4. The co-composting process exhibited a higher temperature (60 - 67°C) in the thermophilic phase followed by curing phase after four weeks of treatment. Meanwhile, pH of the composting pile (8.1 - 8.6) was almost constant during the process and moisture content was reduced from 64.5% (initial treatment) to52.0% (final matured compost). The use of pressed-shredded EFB as a main carbon source and bulking agent contributed to the optimum oxygen level in the composting piles (10 - 15%). The biodegradation of composting materials is shown by the reduction of cellulose (34.0%) and hemicellulose (27.0%) content towards the end of treatment. In addition, considerable amount of nutrients and low level of heavy metals were detected in the final matured compost. It can be concluded that the addition of POME anaerobic sludge into the pressed-shredded EFB composting process could produce acceptable and consistent quality of compost product in a short time

Effect of Palm Oil Mill Sterilization Process on the Physicochemical Characteristics and Enzymatic Hydrolysis of Empty Fruit Bunch

Sterilization process of oil palm fruits by-product can be satisfactorily used as alternative degradation method in production of value-added products from Empty Fruit Bunch (EFB). It could be considered as an auto hydrolysis technique in the regular pre-treatment methods. Other studies on lignocelluloses showed that they increase the pore volume of the wood which increases the available surface area for the enzyme. Changes in structure and properties of the EFB cellulose caused by sterilization were investigated by x-ray diffractometry and enzymatic hydrolysis of cellulosic biomass for fermentable sugar production (glucose). The enzymatic hydrolysis results showed that the highest hydrolysis of 53.77±1.38% (g/g biomass) conversion was obtained in EFB after 72 h incubation with glucose production, (Yp/x) of 12.55±0.33 g L-1. The increase in Crystallinity Index (CrI) of sterilized biomass increased the yield of glucose (g L-1) up to 44.55% compared to Fresh Fruit Bunches (FFB) as a control. Results obtained appear to be commercial significance showing the potential of sterilization process in a palm oil mill as a zero cost pre-treatment for the effective utilization of empty fruit bunch biomass for value added production from the palm oil industry