Langevin dynamics simulation of polymer-assisted virus-like assembly

Starting from a coarse grained representation of the building units of the minute virus of mice and a flexible polyelectrolyte molecule, we have explored the mechanism of assembly into icosahedral structures with the help of Langevin dynamics simulations and the parallel tempering technique. Regular icosahedra with appropriate symmetry form only in a narrow range of temperature and polymer length. Within this region of parameters where successful assembly would proceed, we have systematically investigated the growth kinetics. The assembly of icosahedra is found to follow the classical nucleation and growth mechanism in the absence of the polymer, with the three regimes of nucleation, linear growth, and slowing down in the later stage. The calculated average nucleation time obeys the laws expected from the classical nucleation theory. The linear growth rate is found to obey the laws of secondary nucleation as in the case of lamellar growth in polymer crystallization. The same mechanism is seen in the simulations of the assembly of icosahedra in the presence of the polymer as well. The polymer reduces the nucleation barrier significantly by enhancing the local concentration of subunits via adsorbing them on their backbone. The details of growth in the presence of the polymer are also found to be consistent with the classical nucleation theory, despite the smallness of the assembled structures.

Optimization of ozonation process for the reduction of excess sludge production from activated sludge process of sago industry wastewater using central composite design

Sago industries effluent containing large amounts of organic content produced excess sludge which is a serious problem in wastewater treatment. In this study ozonation has been employed for the reduction of excess sludge production in activated sludge process. Central composite design is used to study the effect of ozone treatment for the reduction of excess sludge production in sago effluent and to optimise the variables such as pH, ozonation time, and retention time. ANOVA showed that the coefficient determination value (R(2)) of VSS and COD reduction were 0.9689 and 0.8838, respectively. VSS reduction (81%) was achieved at acidic pH 6.9, 12 minutes ozonation, and retention time of 10 days. COD reduction (87%) was achieved at acidic pH 6.7, 8 minutes of ozonation time, and retention time of 6 days. Low ozonation time and high retention time influence maximum sludge reduction, whereas low ozonation time with low retention time was effective for COD reduction.

Encapsulation of a polyelectrolyte chain by an oppositely charged spherical surface

Using the ground state dominance approximation and a variational theory, we study the encapsulation of a polyelectrolyte chain by an oppositely charged spherical surface. The electrostatic attraction between the polyelectrolyte and the surface and the entropy loss of the encapsulated polyelectrolyte chain dictate the optimum conditions for encapsulation. Two scenarios of encapsulation are identified: entropy-dominated and adsorption-dominated encapsulation. In the entropy-dominated encapsulation regime, the polyelectrolyte chain is delocalized, and the optimum radius of the encapsulating sphere decreases with increasing the attraction. In the adsorption-dominated encapsulation regime, the polyelectrolyte chain is strongly localized near the surface, and the optimum radius increases with increasing the attraction. After identifying a universal encapsulation parameter, the dependencies of the optimum radius on the salt concentration, surface charge density, polymer charge density, and polymer length are explored.

Comparison of PCR based marker systems for genetic analysis in different cultivars of mango

Native diversity is well represented in northern and eastern parts of India for mango. We evaluated three important polymerase chain reaction (PCR) based marker techniques viz., random amplified polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and directed amplified mini satellite DNA (DAMD) and examined their suitability for depicting genetic relationships and discrimination among closely related group of 46 mango varieties grown in the different agro-ecological zones in Uttar Pradesh, Bihar and West Bengal. Nine RAPD, eleven ISSR and four DAMD primers generated 110, 160 and 43 discrete fragments, respectively, accounting for polymorphism of 87.3, 79.83 and 83.72%, respectively. Cumulative analysis of these markers resulted in comprehensive UPGMA based dendrogram where in native mangoes representing important breeding lines and varieties from Uttar Pradesh fall more or less in separate cluster, while Bihar and West Bengal cultivars represent genetically different lineage forming distinct separate cluster. The prime focus on the study was towards identification of genetic variability that warrants establishing origin and molecular evolution of mango cultivars of eastern and northern India because they are the rich gene pool for conservation. Highest diversity index (DI) and polymorphic information content (PIC) values were found in DAMD indicating it to be more informative than others. Similarly, high effective multiplex ratio (EMR) and marker index (MI) were recorded by ISSR reflecting ability to simultaneously detect a large number of bands. The study accomplished establishing genetic relationship and also DNA fingerprint development. The data is also useful for mapping studies for gene identification.

Production and characterization of carboxymethyl cellulase from Paenibacillus polymyxa using mango peel as substrate

Mango peel, a solid mango processing waste, comprises 15-20% of total fruit weight. This, being a rich source of lignocelluloses, was used as substrate for carboxymethyl cellulase (CMCase) production using Paenibacillus polymyxa. Maximum CMCase production (7.814 U mg(-1)) was observed in a medium containing 7% mango peel (w/v) with 1.5% ammonium sulphate (w/v) at 37 degrees C and pH 5.5. Purification to an extent of 28.24 fold was achieved by affinity column chromatography. Bands corresponding to 26.5 and 34.0 kDa molecular sizes were observed on 12% denaturing Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) while of 72 kDa on 10% non-denaturing Native-PAGE, proving its heteromeric multienzyme nature. The enzyme was stable over a range of 20-60 degrees C and pH of 4.0-7.5. Michaelis-Menten equation constant (Km and Vmax) values of purified CMCase were 8.73 mg ml(-1) and 17.805 mM ml(-1) min(-1), respectively.

Ruthenium(II) hydrazone Schiff base complexes: synthesis, spectral study and catalytic applications

Ruthenium(II) hydrazone Schiff base complexes of the type [RuCl(CO)(B)(L)] (were B=PPh(3), AsPh(3) or Py; L=hydrazone Schiff base ligands) were synthesized from the reactions of hydrazone Schiff base ligand (obtained from isonicotinoylhydrazide and different hydroxy aldehydes) with [RuHCl(CO)(EPh(3))(2)(B)] (where E=P or As; B=PPh(3), AsPh(3) or Py) in 1:1 molar ratio. All the new complexes have been characterized by analytical and spectral (FT-IR, electronic, (1)H, (13)C and (31)P NMR) data. They have been tentatively assigned an octahedral structure. The synthesized complexes have exhibited catalytic activity for oxidation of benzyl alcohol to benzaldehyde and cyclohexanol to cyclohexanone in the presence of N-methyl morpholine N-oxide (NMO) as co-oxidant. They were also found to catalyze the transfer hydrogenation of aliphatic and aromatic ketones to alcohols in KOH/Isopropanol.

Colour, myoglobin denaturation and storage stability of raw and cooked mutton chops at different end point cooking temperature

In our study effect of different end point temperature (51 °C, 65 °C, 71 °C and 79 °C) on physicochemical and storage stability of mutton chops were evaluated. The L* (lightness) value and b* (yellowness) increased (P < 0.05) in cooked mutton chops than the raw mutton. The a* value (redness) decreased (P < 0.05) as end point temperature increased. As internal cooking temperature increased soluble myoglobin content decreased with a corresponding increase in percent myoglobin denatured. Raw mutton chops (uncooked) had lower level of oxidation (less TBA values) than cooked mutton irrespective of storage length. Initial APC of raw and cooked mutton chops ranged from log 1.75 to log 3.73 and was lower in higher end point cooking temperature. It can be concluded that as end point temperature increased, mutton chops appear less red and raw mutton had lower level of oxidation than cooked mutton chops.

Pattern formation in drying droplets of polyelectrolyte and salt

We have discovered spectacular patterns formed by drying aqueous drops of sodium poly(styrene sulfonate) containing fixed amounts of sodium chloride. Crystallization of salt molecules takes place at a critical concentration and several factors such as the polyelectrolyte concentration and humidity affect the final patterns formed. The observed patterns include concentric rings, needle-like structures, chains of triangular-shaped crystallites, etc. We describe the observed phenomenology accompanied by a theoretical model for the occurrence of concentric rings.

Electrochemical oxidation of tannic acid contaminated wastewater by RuO2/IrO2/TaO2-coated titanium and graphite anodes

The electrochemical oxidation of tannic acid contaminated wastewater by RuO2/IrO2/TaO2-coated titanium and graphite anodes has been investigated. The effect of the process variables, such as initial pH, current density, processing time, concentration of the electrolyte and anode materials, on the degradation of tannic acid was studied. During the various stages of electrolysis, parameters such as COD, chloride ion concentration and UV-Vis spectra were examined and discussed. The maximum chemical oxygen demand (COD) removal efficiency of 94% was achieved at pH 5, operated at the current density of 8.10 mA/cm2, electrolyte (NaCl) concentration of 0.1 M and at 60 min of electrolysis using graphite anodes. The experimental results showed that the electrochemical oxidation process could effectively reduce the COD from the tannic acid contaminated wastewater. An acidic pH showed the maximum reduction of COD compared with neutral and alkaline pH. Increase in current density, process time and electrolyte (NaCl) concentration with the increase in COD removal. Graphite anodes showed maximum removal of COD and better tannic acid degradation when compared with RuO2/IrO2/TaO2-coated titanium anodes.

Polymer translocation through alpha-hemolysin pore with tunable polymer-pore electrostatic interaction

We have measured the ionic current blockages produced by single molecules of sodium poly(styrene sulfonate) passing through an alpha-hemolysin protein pore under an electric field. Most of the blockage events were composed of one or two blockage levels of ionic current. By analyzing the statistics of different event types for different polymer lengths, applied voltages, and pH conditions, we have identified the molecular mechanism behind the two-level blockages. Our analysis of the data shows that not all blockages are successful translocation events and the propensity of successful translocation can be tuned by pH gradients across the protein pore. We interpret our results as the change in protein-polymer interaction via protonation of charged amino acid residues of alpha-hemolysin pore. In addition, we have constructed a stochastic theory for polymer translocation through alpha-hemolysin pore with tunable polymer-pore interactions. The theoretical calculations capture many features observed in our experiments.

Effects of salt and ammonium hydroxide on the quality of ground buffalo meat

The objective of this study was to evaluate the effects of ammonium hydroxide (AH) and sodium chloride on the quality of ground buffalo meat patties. Ground buffalo meat was treated with distilled water (control), 0.5% v/w AH, 1.0% v/w AH, 2.0% v/w AH and 1.0% w/w sodium chloride was added for all the samples. Treatment with AH increased (P<0.05) the pH and water holding capacity (WHC) of ground buffalo meat patties during storage relative to their controls. Hunterlab a* (redness) and chroma values increased (P<0.05) and hue decreased (P<0.05) in all AH treated samples in comparison to controls during storage. Ammonium hydroxide significantly (P<0.05) inhibited metmyoglobin formation compared to control after 3rd day of storage. There was a significant (P<0.05) reduction in thiobarbituric acid reactive substances (TBARS) values in all AH treated samples compared to control throughout storage. These results indicate the potential antioxidant and myoglobin redox stabilizing effect of AH in ground buffalo meat patties.

Effect of chilling, polyphosphate and bicarbonate on quality characteristics of broiler breast meat

1. An experiment was conducted to assess the effect of tetrasodium pyrophosphate and sodium bicarbonate on colour and sensory attributes of pre- and post-chilled breast meat. 2. Three groups of 6 halves of breasts (pre-chill) immediately after slaughter were treated with 3% tetrasodium pyrophosphate, 3% sodium bicarbonate in 2% NaCl or 2% NaCl alone (control); the remaining 6 halves (post-chill) were stored overnight at 4 degrees C and then treated similarly. Both the pre- and post-chill samples were held at 4 degrees C for 24 h and pH, water holding capacity, cooking loss, CIE colour values and sensory attributes were recorded. 3. Chilling had few effects on the meat characteristics measured in this study. 4. Treatment with phosphate and bicarbonate increased pH in both the pre- and post-chill groups. Treated breasts exhibited lower L* and higher a* value (more red) than controls. 5. A sensory evaluation study revealed improvements in colour and other sensory attributes of cooked broiler breast meat in all treated samples compared to the control. 6. The findings suggest that tetrasodium pyrophosphate and sodium bicarbonate, when injected post mortem, will have beneficial effects on several physico-chemical (pH, colour, WHC %, cooking loss) and sensory attributes of broiler meat. However, phosphate had a smaller effect than bicarbonate.

Chiral symmetry breaking in crystals of achiral polymers

Many achiral polymers crystallize into spherulites with gigantic chirality, as is evident from spectacular images of periodic banding observed in a polarized optical microscope, arising from the twisting of the lamellae making up the spherulites. We present a new mechanism of the spontaneous chiral symmetry breaking, by accounting for topological defects in finite crystalline ribbons made of achiral molecules in equilibrium. We show that disclinations stabilize a twisted helicoidal ribbon, with spontaneous selection of its width and chiral period, which are proportional to each other, as a universal law.

Theory of capture rate in polymer translocation

The translocation of macromolecules through a nanopore requires the impingement of the molecules at the pore followed by threading through the pore. While most of the discussion on the translocation phenomenon focused so far on the threading process, the phenomenology on the frequency of encounters between the polymer and the pore exhibits diverse features in terms of polymer length, solution conditions, driving force, and pore geometry. We derive a general theory for the capture rate of polyelectrolyte molecules and the probability of successful translocation through a nanopore, under an externally imposed electric field. By considering the roles of entropic barrier at the pore entrance and drift of the polyelectrolyte under the electric field, we delineate two regimes: (a) entropic barrier regime and (b) drift regime. In the first regime dominated by the entropic barrier for the polyelectrolyte, the capture rate is an increasing nonlinear function in the electric field and chain length. In the drift regime, where the electric field dwarfs the role of entropic barriers, the capture rate is independent of chain length and linear in electric field. An analytical formula is derived for the crossover behavior between these regimes, and the general results are consistent with various experimentally observed trends.

Detection of cyclodiene pesticide residues in buffalo meat and effect of cooking on residual level of endosulfan

Levels of cyclodiene pesticides (aldrin, α-endosulfan, β-endosulfan, endosulfan sulfate and heptachlor) residues in muscle, liver and kidney tissues of buffalo were estimated. The effects of common cooking methods (microwave cooking, boiling, broiling and pressure cooking) on the levels of endosulfan were determined. Aldrin and total endosulfan (α-endosulfan, β-endosulfan, endosulfan sulfate) residues were found in 42.86 and 64.29% of buffalo tissue samples, with overall mean residual concentration of 0.013 and 0.055 ppm, respectively. However, the levels of these residues were well below the maximum residue limit (MRL: aldrin 0.2 ppm; endosulfan 0.1 ppm) specified by national and international regulatory bodies. Cooking of endosulfan (Endoin 35 EC) spiked meat resulted in 58.33-64.59% reduction in α-endosulfan and 55.93-61.60% reduction in β-endosulfan. Among the cooking methods, pressure cooking was most effective in reducing both α- and β-endosulfan.

Charge regularization in phase separating polyelectrolyte solutions

Theoretical investigations of phase separation in polyelectrolyte solutions have so far assumed that the effective charge of the polyelectrolyte chains is fixed. The ability of the polyelectrolyte chains to self-regulate their effective charge due to the self-consistent coupling between ionization equilibrium and polymer conformations, depending on the dielectric constant, temperature, and polymer concentration, affects the critical phenomena and phase transitions drastically. By considering salt-free polyelectrolyte solutions, we show that the daughter phases have different polymer charges from that of the mother phase. The critical point is also altered significantly by the charge self-regularization of the polymer chains. This work extends the progress made so far in the theory of phase separation of strong polyelectrolyte solutions to a higher level of understanding by considering chains which can self-regulate their charge.