Dark fermentative biohydrogen production by mesophilic bacterial consortia isolated from riverbed sediments

Dark fermentative bacterial strains were isolated from riverbed sediments and investigated for hydrogen production. A series of batch experiments were conducted to study the effect of pH, substrate concentration and temperature on hydrogen production from a selected bacterial consortium, TERI BH05. Batch experiments for fermentative conversion of sucrose, starch, glucose, fructose, and xylose indicated that TERI BH05 effectively utilized all the five sugars to produce fermentative hydrogen. Glucose was the most preferred carbon source indicating highest hydrogen yields of 22.3 mmol/L. Acetic and butyric acid were the major soluble metabolites detected. Investigation on optimization of pH, temperature, and substrate concentration revealed that TERI BH05 produced maximum hydrogen at 37 °C, pH 6 with 8 g/L of glucose supplementation and maximum yield of hydrogen production observed was 2.0–2.3 mol H₂/mol glucose. Characterization of TERI BH05 revealed the presence of two different bacterial strains showing maximum homology to Clostridium butyricum and Clostridium bifermentans.     

A porous scaffold for bone tissue engineering/45S5 Bioglass<Superscript>®</Superscript> derived porous scaffolds for co-culturing osteoblasts and endothelial cells

One of the major factors in the therapeutic success of bone tissue engineered scaffolds is the ability of the construct to vascularise post implantation. One of the approaches for improving vascularisation within scaffolds has been to co-culture human umbilical vein endothelial cells (HUVECS) with human osteoblasts (HOBS), which may then promote vascularisation and facilitate tissue regeneration. However, in order to mimic a natural physiological niche it is vital that the scaffold is able to support and promote the proliferation of both cell types and thus become a viable tissue engineered construct. In this study we report the development of a porous bioactive glass–ceramic construct and examine the interaction with human umbilical vein endothelial cells (HUVEC’s) and human osteoblast-like cell both in mono and co-culture. The study clearly demonstrated that the scaffolds were able to support both endothelial and human osteoblast cell proliferation both in mono and co-culture. A comparison of the proliferation response of HUVEC and HOB in mono-culture on the test scaffolds and the commercial porous hydroxyapatite was assessed over a 28 day period (4, 7, 14, 21 and 28 days), using alamar Blue^TM assay. Proliferation of HOB cells seeded in the scaffolds was consistently shown to be above those observed on commercial HA scaffolds.     

The role of the ionomer glass component in polyacid-modified composite resin dental restorative materials

In order to model the processes that occur within polyacid-modified composite resin ("compomer") dental restoratives, a series of experiments has been carried out with silanated and silane-free ionomer glass G338, and silanated and silane-free unreactive glass (Raysorb T-4000). In an acid-base reaction with dental grade aqueous maleic acid-acrylic acid copolymer solution, the setting time of the silanted G338 was found to be 9 min, compared with 5 min for the silane-free glass. Inclusion of each glass in an experimental composite resin system showed that the formulations which contained G338 absorbed more water than the formulations which contained Raysorb T-4000, regardless of whether or not the glass was silanted. Biaxial flexure strength was superior for experimental composites containing Raysorb T-4000, with highest results being obtained with the silanated glass. Overall these results demonstrate that silanation of the filler is essential for optimal physical properties but that, for the ionomer glass, it inhibits the acid-base reaction. The presence of ionomer glass led to an increase in water uptake compared with the unreactive glass, regardless of the presence of silane.     

Design of a Robust Optimal Decentralized PI Controller Based on Nonlinear Constraint Optimization For Level Regulation: An Experimental Study

This paper presents the development of a new robust optimal decentralized PI controller based on nonlinear optimization for liquid level control in a coupled tank system. The proposed controller maximizes the closed-loop bandwidth for specified gain and phase margins, with constraints on the overshoot ratio to achieve both closed-loop performance and robustness. In the proposed work, a frequency response fitting model reduction technique is initially employed to obtain a first order plus dead time (FOPDT) model of each higher order subsystem. Furthermore, based on the reduced order model, a proposed controller is designed. The stability and performance of the proposed controller are verified by considering multiplicative input and output uncertainties. The performance of the proposed optimal robust decentralized control scheme has been compared with that of a decentralized PI controller. The proposed controller is implemented in real-time on a coupled tank system. From the obtained results, it is shown that the proposed optimal decentralized PI controller exhibits superior control performance to maintain the desired level, for both the nominal as well as the perturbed case as compared to a decentralized PI controller.      

Application of support vector regression analysis to estimate total organic carbon content of Cambay shale in Cambay basin,India – a case study

The objective of the present study is to estimate total organic carbon (TOC) content over the entire thickness of Cambay Shale, in the boreholes of Jambusar–Broach block of Cambay Basin, India. To achieve this objective, support vector regression (SVR), a supervised data mining technique, has been utilized using five basic wireline logs as input variables. Suitable SVR model has been developed by selecting epsilon-SVR algorithm and varying three different kernel functions and parameters like gamma and cost on a sample dataset. The best result is obtained when the radial-basis kernel function with gamma = 1 and cost = 1, are used. Finally, the performance of developed SVR model is compared with the ΔlogR method. The TOC computed by SVR method is found to be more precise than the ΔlogR method, as it has better agreement with the core-TOC. Thus, in the present study area, the SVR method is found to be a powerful tool for estimating TOC of Cambay Shale in a continuous and rapid manner.     

Evaluation of in situ albumin binding surfaces: a study of protein adsorption and platelet adhesion

Surface modification strategies that take advantage of the passivation effects of albumin are important in the development of biomaterial surfaces. In this study, linear peptides (LP1, LP2) and a small chemical ligand (SCL) with albumin binding affinities were grafted onto silane functionalized silicon substrates. Surfaces were characterized with contact angle and ellipsometric measurements, and densities of immobilized ligands were assessed spectroscopically. Ellipsometrically measured thickness correlated with the predicted molecular lengths of grafted moieties. Contact angle analysis indicated that the LP1 and LP2 functionalized surfaces were hydrophilic compared to SCL functionalized and control surfaces. Adsorption of albumin from human serum was evaluated and quantified via specific enzyme-linked immunosorbent assays and 2D gel electrophoresis. The following trend was noted for surface adsorbed albumin: LP1 > LP2 > SCL > C, with LP1 derivatized surfaces having ~2.450 μg/cm² of bound albumin. LP1 derivatized surfaces possessed the least number of adsorbed platelets with rounded platelet morphology when compared to control surface.     

QCA Circuits for Robust Coplanar Crossing

In this paper, different circuits of Quantum-dot Cellular Automata (QCA) are proposed for the so-called coplanar crossing. Coplanar crossing is one of the most interesting features of QCA because it allows for mono-layered interconnected circuits, whereas CMOS technology needs different levels of metalization. However, the characteristics of the coplanar crossing make it prone to malfunction due to thermal noise or defects. The proposed circuits exploit the majority voting properties of QCA to allow a robust crossing of wires on the Cartesian plane. This is accomplished using enlarged lines and voting. A Bayesian Network (BN) based simulator is utilized for evaluation; results are provided to assess robustness in the presence of cell defects and thermal effects. The BN simulator provides fast and reliable computation of the signal polarization versus normalized temperature. Simulation of the wire crossing circuits at different operating temperatures is provided with respect to defects and a quantitative metric for performance under temperature variations is proposed and assessed.     

Fermentative hydrogen production in recombinant Escherichia coli harboring a [FeFe]-hydrogenase gene isolated from Clostridium butyricum

The [FeFe]-hydrogenase (hydA) from Clostridium butyricum TERI BH05-2 strain was isolated to elucidate its molecular characterization. A 1953 bp DNA fragment encompassing the ORF and the putative promoter region of hydA gene was PCR amplified and subcloned into pGEM^®-T-Easy cloning vector (pGEM^®-T-hydA). The hydA DNA sequence revealed the presence of a 1725 bp length ORF (including the stop codon) encoding 574 amino acids with a predicted isoelectric point and molecular mass of 6.8 and 63097.67 Da, respectively. The hydA ORF was PCR amplified from pGEM^®-T-hydA and inserted into a prokaryotic expression vector to create a recombinant plasmid (pGEX-5X-hydA) and transformed into Escherichia coli BL-21. The recombinant E. coli BL-21 was investigated for fermentative hydrogen production under anaerobic condition from glucose. Heterologous expression of the Clostridium butyricum hydA resulted in 1.9 fold increase in hydrogen productivity as compared to that from the wild type strain, C. butyricum TERI BH05-2. The hydrogen yield of the recombinant strain was 3.2 mol H₂/mol glucose, 1.68 fold higher than the wild type parent strain.     

Cooperative formation control of autonomous underwater vehicles: An overview

Formation control is a cooperative control concept in which multiple autonomous underwater mobile robots are deployed for a group motion and/or control mission. This paper presents a brief review on various cooperative search and formation control strategies for multiple autonomous underwater vehicles (AUV) based on literature reported till date. Various cooperative and formation control schemes for collecting huge amount of data based on formation regulation control and formation tracking control are discussed. To address the challenge of detecting AUV failure in the fleet, communication issues, collision and obstacle avoidance are also taken into attention. Stability analysis of the feasible formation is also presented. This paper may be intended to serve as a convenient reference for the further research on formation control of multiple underwater mobile robots.     

Using core-periphery structure to predict high centrality nodes in time-varying networks

Vertices with high betweenness and closeness centrality represent influential entities in a network. An important problem for time varying networks is to know a-priori, using minimal computation, whether the influential vertices of the current time step will retain their high centrality, in the future time steps, as the network evolves. In this paper, based on empirical evidences from several large real world time varying networks, we discover a certain class of networks where the highly central vertices are part of the innermost core of the network and this property is maintained over time. As a key contribution of this work, we propose novel heuristics to identify these networks in an optimal fashion and also develop a two-step algorithm for predicting high centrality vertices. Consequently, we show for the first time that for such networks, expensive shortest path computations in each time step as the network changes can be completely avoided; instead we can use time series models (e.g., ARIMA as used here) to predict the overlap between the high centrality vertices in the current time step to the ones in the future time steps. Moreover, once the new network is available in time, we can find the high centrality vertices in the top core simply based on their high degree. To measure the effectiveness of our framework, we perform prediction task on a large set of diverse time-varying networks. We obtain F1-scores as high as 0.81 and 0.72 in predicting the top m closeness and betweenness centrality vertices respectively for real networks where the highly central vertices mostly reside in the innermost core. For synthetic networks that conform to this property we achieve F1-scores of 0.94 and 0.92 for closeness and betweenness respectively. We validate our results by showing that the practical effects of our predicted vertices match the effects of the actual high centrality vertices. Finally, we also provide a formal sketch demonstrating why our method works.