Biodegradation of pyridine by the new bacterial isolates S. putrefaciens and B. sphaericus

In this study, two bacterial strains capable of utilizing pyridine as a sole carbon source were isolated from biofilters. Based on the biochemical test, the organisms were identified as Shewanella putrefaciens and Bacillus sphaericus. In liquid cultures, S. putrefaciens and B. sphaericus degraded pyridine quite effectively up to 500 mg L(-1). S. putrefaciens degrades 500 mg L(-1) of pyridine completely within 140 h, whereas the B. sphaericus degrades 500 mg L(-1) of pyridine only nearly 75% and takes a longer duration of 150 h. S. putrefaciens used pyridine as sole carbon and energy source better than B. sphaericus. Monod's and Haldane's inhibitory growth models were used to obtain maximum specific growth rate (micro(max)), half saturation (K(s)) and substrate inhibition (K(i)) constant for pyridine by using S. putrefaciens and B. sphaericus. The high value of K(i) for S. putrefaciens than B. sphaericus indicates that the inhibition effect can be observed only in a high concentration range. The S. putrefaciens degrades pyridine with a faster rate than B. sphaericus. S. putrefaciens can be used effectively for the treatment of pyridine bearing wastewater and as an inoculum in a biofilter treating pyridine-laden gas.     

Treatment of arsenic contaminated water in a laboratory scale up-flow bio-column reactor

The present paper describes the observations on the treatment of arsenic contaminated synthetic industrial effluent in a bio-column reactor. Ralstonia eutropha MTCC 2487 has been immobilized on the granular activated carbon (GAC) bed in the column reactor. The synthetic water sample containing As(T) (As(III):As(V)=1:1), Fe, Mn, Cu and Zn at the initial concentrations of 25, 10, 2, 5, 10 ppm, respectively, was used. Concentrations of all the elements have been found to be reduced below their permissible limits in the treated water. The significant effect of empty bed contact time (EBCT) and bed height on the arsenic removal was observed in the initial stage. However, after some time of operation (approximately 3-4 days) no such effect was observed. Removal of As(III) and As(V) was almost similar after approximately 2 days of operation. However, at the initial stage As(V) removal was slightly more than that of As(III). In absence of washing, after approximately 4-5 days of operation, the bio-column reactor was observed to act as a GAC column reactor based on physico-chemical adsorption. Like arsenic, the percent removals of Fe, Mn, Cu and Zn also attained minimum after approximately 1 day and increased significantly to the optimum value within 3-4 days of operation. Dissolved oxygen (DO) has been found to decrease along with the increasing bed height from the bottom. The pH of the solution in the reactor has increased slightly and oxidation-reduction potential (ORP) has decreased with the time of operation.     

Analysis of dispersion coefficient of bubble motion and velocity characteristic factor in down and upflow bubble column reactor

Dispersion coefficient of bubble motion based on velocity distribution theory has been analyzed in up and downward gas-liquid two-phase contactor. The intensity of dispersion of phase depends on motion of the dispersed phase and the characteristics of velocity distribution. In this paper the effects of operating and geometric variables on the dispersion coefficient of bubble motion and the characteristic factor of velocity distribution have been analyzed within the range of column diameter 0.10-2.5 m, superficial liquid velocity, 0.04-0.21 m/s and superficial gas velocity 0.41-3.16 mm/s. From the different developed model of longitudinal dispersion coefficient of liquid, comparison of dispersion coefficient of bubble motion and characteristic feature of velocity distribution in down and upflow two-phase contactor has been reported. Also the functionalities of dispersion coefficient of bubble motion and velocity characteristic factor have been developed with operating variables. The condition for dispersion based on velocity pattern has also been discussed in the present work. The present analysis on the dispersion coefficient of bubble motion and velocity distribution factor associated with the knowledge of the liquid phase dispersion in two-phase contactor can give insight into a further understanding and modeling of multiphase reactor in industrial applications.     

Fuzzy divergence, probability measure of fuzzy events and image thresholding

A new measure called divergence between two fuzzy sets is introduced along with a few properties. Its application to clustering problems is indicated and applied to an object extraction problem. A tailored version of the probability measure of a fuzzy event is also used for image segmentation. Both parametric and non-parametric probability distributions are considered in this regard.     

Effect of Pluronic F-127 debinding temperature on the sintering and densification of alumina by direct ink writing

Hydrogel-based alumina (Al₂O₃) inks were prepared using Pluronic F-127 with 65 wt% of solid loading (Al₂O₃). The Al₂O₃ inks were deposited, and the freestanding samples were studied using TGA/DTA. Significant weight loss was observed between 180 and 360°C. A two-stage hydrogel debinding process of Al₂O₃ samples was carried out at 180 and 360°C with holding times of 30, 60, 90, 120, and 150 min. The Al₂O₃ samples were then sintered at 1600°C. X-ray diffraction was used for the phase analysis of the alumina inks, and a scanning electron microscope was used microstructural analysis. Based on the TGA/DTA analysis, a two-stage debinding process was adopted. Significant effect of hydrogel debinding temperature was observed on the sintering and densification behavior of alumina. It was observed that the porosities in the alumina samples were increasing when the debinding time was increased from 30 to 150 min, with the debinding temperature at 180 and 360°C. Moreover, the nature of the porosities was changing from closed porosities to interconnected porosities.     

Unfolding the Mystery Behind the Onset of Chondrocyte Hypertrophy during Chondrogenesis: Toward Designing Advanced Permanent Cartilage-mimetic Biomaterials

Successful recapitulation of the anatomical microarchitecture and biomechanics of the native articular cartilage under in vitro culture conditions is still an elusive topic of research. The major roadblock lies in maintaining the stable chondrogenic phenotype in vivo or under long-term in vitro conditions. Tissue engineers worldwide has coined this aberrant loss of permanent cartilage characteristics to transient cartilage form as “chondrocyte hypertrophy”. Although the following has been validated through the expression of a few known markers but very little is understood regarding the molecular mechanism that dwells underneath. This review summarizes the precise aetiology behind the development and progression of the hypertrophic phenotype in chondrocytes under in vitro chondrogenic conditions. Based on the current literature survey, it is deciphered that the type of cell utilized (chondrocytes or stem cells), the chondrogenic culture conditions (growth factors/biochemical mediators) and the culture microenvironment (oxygen tension, mechanical loading) during chondrogenesis have a direct correlation with the dysregulated activity of the chondrogenic signaling pathways corroborating the onset of hypertrophic maturation of chondrocytes. Furthermore, it is critically analyzed whether to completely inhibit these hypertrophy-inducing signaling pathways or apply a brake in terms of time-dependent dose due to their functional duality role in chondrogenesis.     

Secondary-Phase-Induced Charge–Discharge Performance Enhancement of Co-Free High Entropy Spinel Oxide Electrodes for Li-Ion Batteries

High entropy oxide (HEO) has emerged as a new class of anode material for Li-ion batteries (LIBs) by offering infinite possibilities to tailor the charge–discharge properties. While the advantages of single-phase HEO anodes are realized, the effects of a secondary phase are overlooked. In this study, two kinds of Co-free HEOs are prepared, containing Cr, Mn, Fe, Ni, and Zn, for use as LIB anodes. One is a plain cubic-structure high entropy spinel oxide HESO (C) prepared using a solvothermal method. The other HESO (C+T) contains an extra secondary phase of tetragonal spinel oxide and is prepared using a hydrothermal method. It is demonstrated that the secondary tetragonal spinel phase introduces phase boundaries and defects/oxygen vacancies within HESO (C+T), which improve the redox kinetics and reversibility during electrode lithiation/delithiation. Density functional theory calculation is performed to assess the phase stability of cubic spinel, tetragonal spinel, and rock-salt structures, and validate the cycling stability of the electrodes upon charging–discharging. The secondary-phase-induced rate capability and cyclability enhancement of HEO electrodes are for the first time demonstrated. A HESO (C+T)||LiNi_0.8Co_0.1Mn_0.1O₂ full cell is assembled and evaluated, showing a promising gravimetric energy density of ≈610 Wh kg⁻¹ based on electrode-active materials.