Study of Uniaxial Tensile Properties of Hexagonal Boron Nitride Nanoribbons

Uniaxial tensile properties of hexagonal boron nitride nanoribbons and dependence of these properties on temperature, strain rate, and the inclusion of vacancy defects have been explored with molecular dynamics simulations using Tersoff potential. The ultimate tensile strength of pristine hexagonal boron nitride nanoribbon of 26 nm x 5 nm with armchair chirality is found to be 100.5 GPa. The ultimate tensile strength and strain have been found decreasing with increasing the temperature while an opposite trend has been observed for increasing the strain rate. Furthermore, the vacancy defects reduce ultimate tensile strength and strain where the effect of bi-vacancy is clearly dominating over point vacancy

On Power Splitting Games in Distributed Computation: The Case of Bitcoin Pooled Mining

Several new services incentivize clients to compete in solving large computation tasks in exchange for financial rewards. This model of competitive distributed computation enables every user connected to the Internet to participate in a game in which he splits his computational power among a set of competing pools — the game is called a computational power splitting game. We formally model this game and show its utility in analyzing the security of pool protocols that dictate how financial rewards are shared among the members of a pool. As a case study, we analyze the Bitcoin cryptocurrency which attracts computing power roughly equivalent to billions of desk- top machines, over 70% of which is organized into public pools. We show that existing pool reward sharing protocols are insecure in our game-theoretic analysis under an attack strategy called the “block withholding attack”. This attack is a topic of debate, initially thought to be ill-incentivized in today’s pool protocols: i.e., causing a net loss to the attacker, and later argued to be always profitable. Our analysis shows that the attack is always well-incentivized in the long-run, but may not be so for a short duration. This implies that existing pool protocols are insecure, and if the attack is conducted systematically, Bitcoin pools could lose millions of dollars worth in months. The equilibrium state is a mixed strategy—that is—in equilibrium all clients are incentivized to probabilistically attack to maximize their payoffs rather than participate honestly. As a result, a part of the Bitcoin network is incentivized to waste resource competing for higher selfish reward

A multi-organ maize metabolic model connects temperature stress with energy production and reducing power generation

Climate change has adversely affected maize productivity. Thereby, a holistic understanding of metabolic crosstalk among its organs is important to address this issue. Thus, we reconstructed the first multi-organ maize metabolicmodel, iZMA6517, and contextualized itwith heat and cold stress transcriptomics data using expression distributed reaction flux measurement (EXTREAM) algorithm. Furthermore, implementing metabolic bottleneck analysis on contextualized models revealed differences between these stresses. While both stresses had reducing power bottlenecks, heat stress had additional energy generation bottlenecks.We also performed thermodynamic driving force analysis, revealing thermodynamics-reducing power-energy generation axis dictating the nature of temperature stress responses. Thus, a temperaturetolerant maize ideotype can be engineered by leveraging the proposed thermodynamics-reducing powerenergy generation axis.We experimentally inoculated maize root with a beneficial mycorrhizal fungus, Rhizophagus irregularis, and as a proof-of-concept demonstrated its efficacy in alleviating temperature stress. Overall, this study will guide the engineering effort of temperature stress-tolerant maize ideotypes

QUANTITATIVE MODEL CHECKING OF DISTRIBUTED PROBABILISTIC SYSTEMS

Ph.DDOCTOR OF PHILOSOPH

Development of a real-time TaqMan assay to detect mendocina sublineage Pseudomonas species in contaminated metalworking fluids

A TaqMan quantitative real-time polymerase chain reaction (qPCR) assay was developed for the detection and enumeration of three Pseudomonas species belonging to the mendocina sublineage (P. oleovorans, P. pseudoalcaligenes, and P. oleovorans subsp. lubricantis) found in contaminated metalworking fluids (MWFs). These microbes are the primary colonizers and serve as indicator organisms of biodegradation of used MWFs. Molecular techniques such as qPCR are preferred for the detection of these microbes since they grow poorly on typical growth media such as R2A agar and Pseudomonas isolation agar (PIA). Traditional culturing techniques not only underestimate the actual distribution of these bacteria but are also time-consuming. The primer-probe pair developed from gyrase B (gyrB) sequences of the targeted bacteria was highly sensitive and specific for the three species. qPCR was performed with both whole cell and genomic DNA to confirm the specificity and sensitivity of the assay. The sensitivity of the assay was 101 colony forming units (CFU)/ml for whole cell and 13.7 fg with genomic DNA. The primer-probe pair was successful in determining concentrations from used MWF samples, indicating levels between 2.9 × 103 and 3.9 × 106 CFU/ml. In contrast, the total count of Pseudomonas sp. recovered on PIA was in the range of \u3c 1.0 × 101 to 1.4 × 105 CFU/ml for the same samples. Based on these results from the qPCR assay, the designed TaqMan primer-probe pair can be efficiently used for rapid (within 2 h) determination of the distribution of these species of Pseudomonas in contaminated MWFs. © 2010 Society for Industrial Microbiology

Molecular cloning of Brevundimonas diminuta for efficacy assessment of reverse osmosis devices

Brevundimonas diminuta is the test organism specified in the United States Environmental Protection Agency\u27s (USEPA) reverse osmosis (RO) treatment device verification protocol. As non-selective growth medium is employed, enumeration of B. diminuta may be impaired due to interference by indigenous heterotrophic bacteria. Thus the microbial removal capability of the filtration system may be incorrectly assessed. As these treatment devices are used in emergency situations, the health of the public could be compromised. The objective of this study was to develop selective approaches for enumerating viable B. diminuta in test water. Two molecular approaches were investigated: expression of a kanamycin resistance gene and expression of a fluorescent protein gene. The USEPA protocol specifies a 0.3 μm cell size, so the expression of the selective markers were assessed following growth on media designed to induce this small cell diameter. The kanR strain was demonstrated to be equivalent to the wild type in cell dimension and survival following exposure to the test water. The kanR strain showed equivalent performance to the wild type in the RO protocol indicating that it is a viable alternative surrogate. By utilizing this strain, a more accurate validation of the RO system can be achieved. © IWA Publishing 2012

Pseudomonas oleovorans subsp. lubricantis subsp. nov., and reclassification of pseudomonas pseudoalcaligenes ATCC 17440T as later synonym of pseudomonas oleovorans ATCC 8062T

Isolate RS1T isolated from used metalworking fluid was found to be a Gram-negative, motile, and nonspore forming rod. Based on phylogenetic analyses with 16S rRNA, isolate RS1T was placed into the mendocina sublineage of Pseudomonas. The major whole cell fatty acids were C18:1ω7c (32.6%), C16:0 (25.5%), and C15:0 ISO 2OH/C16:1ω7c (14.4%). The sequence similarities of isolate RS1T based on gyrB and rpoD genes were 98.9 and 98.0% with Pseudomonas pseudoalcaligenes, and 98.5 and 98.1% with Pseudomonas oleovorans, respectively. The ribotyping pattern showed a 0.60 similarity with P. oleovorans ATCC 8062T and 0.63 with P. pseudoalcaligenes ATCC17440T. The DNA G + C content of isolate RS1T was 62.2 mol.%. The DNA DNA relatedness was 73.0% with P. oleovorans ATCC 8062T and 79.1% with P. pseudoalcaligenes ATCC 17440T. On the basis of morphological, biochemical, and molecular studies, isolate RS1T is considered to represent a new subspecies of P. oleovorans. Furthermore, based on the DNA DNA relatedness ( \u3c 70%), chemotaxonomic, and molecular profile, P. pseudoalcaligenes ATCC 17440T and P. oleovorans ATCC 8062T should be united under the same name; according to the rules of priority, P. oleovorans, the first described species, is the earlier synonym and P. pseudoalcaligenes is the later synonym. As a consequence, the division of the species P. oleovorans into two novel subspecies is proposed: P. oleovorans subsp. oleovorans subsp. nov. (type strain ATCC 8062T = DSM 1045T = NCIB 6576T), P. oleovorans subsp. lubricantis subsp. nov. (type strain RS1T = ATCC BAA-1494T = DSM 21016T). © Springer Science+Business Media, LLC 2009

Determination of the effectiveness of UV radiation as a means of disinfection of metalworking fluids

Microbial contamination of metalworking fluids (MWFs) causes biofouling and degradation and is also associated with several health hazards. Development of an effective control method is therefore essential to reduce microbial loading inMWFs. The present study investigated the efficacy and rapidity of UV radiation as a means of disinfection of MWFs under laboratory conditions to determine parameters that could be used to design an in-line UVreactor for enclosed machines. High and low concentrations (104-107 CFU/mL) of three indicator bacteria, Pseudomonas fluorescens , P. oleovorans subsp. lubricantis and Mycobacterium chelonae, were evaluated both as pure cultures and in combinations. The target organisms were irradiated with a high intensity (192 μW/cm2, 55 W) UV lamp for different exposure time under both static and mixed conditions. For these Pseudomonas species with high concentrations of cells under static conditions, only a 56 % reduction was observed within 10 min of exposure, whereas under mixed condition, a 99 % reduction was achieved within 2 min of exposure. In contrast only 74%reduction was observed for M. chelonae. However, with low concentrations of cells under mixed conditions, a 99.99 % and 82 % reduction in viable count was observed for the Pseudomonas sp. and M. chelonae, respectively. Similar results were observed for mixed culture combinations. Based on these observations high intensity UV in combination with mixing could be successfully used as a means of disinfection of MWFs within a short exposure time and the parameters obtained from the study could be implemented to design a plug flow UV reactor. © Springer-Verlag Berlin Heidelberg and the University of Milan 2013

Inventorizing the modern benthic foraminiferal assemblage from marginal marine environments across the North West coast of Bay of Bengal

Sen, Areen, Saha, Ratul, Sivakumar, Kuppuswamy, Bhadury, Punyasloke (2018): Inventorizing the modern benthic foraminiferal assemblage from marginal marine environments across the North West coast of Bay of Bengal. Zootaxa 4441 (2): 245-260, DOI: 10.11646/zootaxa.4441.2.