Unravelling the potential of low-valent tunable vanadium complexes in the nitrogen reduction reaction (NRR).

Density functional theory calculations have been carried out to investigate the potential of several hitherto unknown low-valent tripodal vanadium complexes towards conversion of dinitrogen to ammonia as a function of different equatorial (PPr and SPr) and bridgehead groups (B, C and Si). All the newly proposed vanadium complexes were probed towards understanding their efficiency in some of the key steps involved in the dinitrogen fixation process. They were found to be successful in preventing the release of hydrazine during the nitrogen reduction reaction.

Adaptive Output Containment Tracking Control for Heterogeneous Wide-Area Networks with Aperiodic Intermittent Communication and Uncertain Leaders.

This paper proposes an adaptive distributed hybrid control approach to investigate the output containment tracking problem of heterogeneous wide-area networks with intermittent communication. First, a clustered network is modeled for a wide-area scenario. An aperiodic intermittent communication mechanism is exerted on the clusters such that clusters only communicate through leaders.

Adaptive optimal control of affine nonlinear systems via identifier-critic neural network approximation with relaxed PE conditions.

This paper considers an optimal control of an affine nonlinear system with unknown system dynamics. A new identifier-critic framework is proposed to solve the optimal control problem. Firstly, a neural network identifier is built to estimate the unknown system dynamics, and a critic NN is constructed to solve the Hamiltonian-Jacobi-Bellman equation associated with the optimal control problem.

Optimal H tracking control of nonlinear systems with zero-equilibrium-free via novel adaptive critic designs.

In this paper, a novel adaptive critic control method is designed to solve an optimal H tracking control problem for continuous nonlinear systems with nonzero equilibrium based on adaptive dynamic programming (ADP). To guarantee the finiteness of a cost function, traditional methods generally assume that the controlled system has a zero equilibrium point, which is not true in practical systems. In order to overcome such obstacle and realize H optimal tracking control, this paper proposes a novel cost function design with respect to disturbance, tracking error and the derivative of tracking error.

Unravelling the Potential of Ylides in Stabilizing Low-Valent Group 13 Compounds: Theoretical Predictions of Stable, Five-Membered Group 13 (Aluminum and Gallium) Carbenoids Capable of Small-Molecule Activation.

Computational investigations provide evidence toward the remarkable ability of strongly electron-donating ylidic functionalities in stabilizing singlet group 13 carbenoids with promising ligand properties. All of the proposed carbenoids are found to be considerably nucleophilic and possess significant singlet-triplet energy separation values. The calculated activation barriers and reaction free energies obtained for the cleavage of different enthalpically strong bonds by these carbenoids are found to be either comparable to or lower than those of the experimentally evaluated aluminum and gallium carbenoids, thereby indicating their potential in small-molecule activation.

Understanding, Modulating, and Leveraging Transannular M → Z Interactions.

Density functional theory calculations have been performed on metallatranes featuring a group 13 elements at the bridgehead position to understand the factors that influence the nature of the M···Z (M = Fe, Co, Ni; Z = Al, Ga, In) interaction present in these complexes and the resultant reactivity at the metal center. The strength of the M···Z interaction increases with the increase in the size and polarizability of the bridgehead group 13 elements. The calculated reaction free energies (Δ° values) for binding of different Lewis bases to the metallatranes are found to be significantly more exergonic for the larger In(III) ions.

Optimal Tracking Control of Nonlinear Multiagent Systems Using Internal Reinforce Q-Learning.

In this article, a novel reinforcement learning (RL) method is developed to solve the optimal tracking control problem of unknown nonlinear multiagent systems (MASs). Different from the representative RL-based optimal control algorithms, an internal reinforce Q-learning (IrQ-L) method is proposed, in which an internal reinforce reward (IRR) function is introduced for each agent to improve its capability of receiving more long-term information from the local environment. In the IrQL designs, a Q-function is defined on the basis of IRR function and an iterative IrQL algorithm is developed to learn optimally distributed control scheme, followed by the rigorous convergence and stability analysis.

Activation of small molecules by cyclic alkyl amino silylenes (CAASis) and germylenes (CAAGes): a theoretical study.

Quantum chemical calculations have been carried out on a series of skeletally modified cyclic alkyl amino silylenes (CAASis) and germylenes (CAAGes) to understand their ligand properties and reactivity towards the activation of a variety of small molecules. The installation of boron or silicon atoms into the ring framework of these silylenes/germylenes led to a dramatic increase in their σ-basicity while the incorporation of ylidic moieties resulted in a sharp reduction of their π-acidity although it did help in increasing the electron donation ability. The calculated values of energy barriers for the activation of H-H, N-H, C-H and Si-H bonds by many of the cyclic silylenes considered here are found to be comparable to those for experimentally evaluated systems, indicating the potential of these computationally designed molecules in small molecule activation and calling for synthetic efforts towards their isolation.

Probing the potential of metalla-N-heterocyclic carbenes towards activation of enthalpically strong bonds.

Density functional theory calculations are employed to explore the reactivity of metalla-N-heterocyclic carbenes (MNHCs) towards activation of a variety of small molecules (H2, NH3, PH3, SiH3Ph and CH4). All the MNHCs considered are found to have a stable singlet ground state and possess suitable electronic properties for their application in small molecule activation. The calculated energy barriers of E-H (E = H, C, N, Si, P) activation for the MNHCs are found to be in agreement with those of the experimentally evaluated cyclic alkyl(amino)carbene (CAAC) and diamidocarbenes (DACs), thereby indicating the activating effect of the incorporation of an ancillary metal center within a cyclic NHC, and highlighting a new, underexplored strategy in achieving difficult bond activations with carbenes.

In search of stable singlet metalla-N-heterocyclic carbenes (MNHCs): a contribution from theory.

Theoretical studies predict that the stability of the singlet state of metalla-N-heterocyclic carbenes (MNHCs) is strongly influenced not only by the substituents at the α-nitrogen atoms and the nature of ligands at the transition metal center but also by the substituents at the carbenic backbone. All the MNHCs were found to have a stable singlet ground state and the computed ΔE values for some of the MNHCs were found to be significantly large and lie within the range of experimentally known carbenes (31.0-84.

First Bis(σ)-borane Complexes of Group 6 Transition Metals: Experimental and Theoretical Studies.

A series of bis(σ)-borane complexes of Group 6 transition metals were prepared by direct dihydroborane coordination to the metal center. Reaction of [M(CO) (PCy ) ] and two dihydroboranes [DurBH ] and [(Me Si) NBH ] (Dur=2,3,5,6-Me C H) yielded bis(σ)-borane complexes fac-[M(CO) (PCy ){η -(H BR)}] (R=Dur; 1: M=Cr, 2: M=W; R=N(SiMe ) ; 3: M=Cr, 4: M=W). In the case of molybdenum, we have isolated an arene complex (5) with [DurBH ] in which the Dur group acts as a η -bound ligand, and with [(Me Si) NBH ] a similar bis(σ)-borane complex was isolated, cis,trans-[Mo(CO) (PCy ) {η -(H BN(SiMe ) }] (6), with a different pattern of auxiliary ligands.

Control of Large-Scale Boolean Networks via Network Aggregation.

A major challenge to solve problems in control of Boolean networks is that the computational cost increases exponentially when the number of nodes in the network increases. We consider the problem of controllability and stabilizability of Boolean control networks, address the increasing cost problem by partitioning the network graph into several subnetworks, and analyze the subnetworks separately. Easily verifiable necessary conditions for controllability and stabilizability are proposed for a general aggregation structure.

Assessing biochemical changes during standardization of fermentation time and temperature for manufacturing quality black tea.

In black tea manufacturing, one of the most important steps is fermentation which influences the quality of tea. The macerated tea leaves were fermented at various temperatures (20, 25, 30, 35 °C) for different duration. Changes in polyphenoloxidase and peroxidase activities, depletion patterns of individual catechins, differences in individual theaflavin levels and formation of thearubigins were measured in leaves during fermentation.

Identification and modeling of genes with diurnal oscillations from microarray time series data.

Behavior of living organisms is strongly modulated by the day and night cycle giving rise to a cyclic pattern of activities. Such a pattern helps the organisms to coordinate their activities and maintain a balance between what could be performed during the "day" and what could be relegated to the "night." This cyclic pattern, called the "Circadian Rhythm," is a biological phenomenon observed in a large number of organisms.

Global proteomics reveal an atypical strategy for carbon/nitrogen assimilation by a cyanobacterium under diverse environmental perturbations.

Cyanobacteria, the only prokaryotes capable of oxygenic photosynthesis, are present in diverse ecological niches and play crucial roles in global carbon and nitrogen cycles. To proliferate in nature, cyanobacteria utilize a host of stress responses to accommodate periodic changes in environmental conditions. A detailed knowledge of the composition of, as well as the dynamic changes in, the proteome is necessary to gain fundamental insights into such stress responses.

Integrative analysis of large scale expression profiles reveals core transcriptional response and coordination between multiple cellular processes in a cyanobacterium.

Background: Cyanobacteria are the only known prokaryotes capable of oxygenic photosynthesis. They play significant roles in global biogeochemical cycles and carbon sequestration, and have recently been recognized as potential vehicles for production of renewable biofuels. Synechocystis sp.

A systems-level analysis of the effects of light quality on the metabolism of a cyanobacterium.

Photosynthetic organisms experience changes in light quantity and light quality in their natural habitat. In response to changes in light quality, these organisms redistribute excitation energy and adjust photosystem stoichiometry to maximize the utilization of available light energy. However, the response of other cellular processes to changes in light quality is mostly unknown.

Effect of continuous light on diurnal rhythms in Cyanothece sp. ATCC 51142.

Background: Life on earth is strongly affected by alternating day and night cycles. Accordingly, many organisms have evolved an internal timekeeping system with a period of approximately 24 hours. Cyanobacteria are the only known prokaryotes with robust rhythms under control of a central clock.

Synaptic adaptation and sustained generation of waves in a model of turtle visual cortex.

Both single and repeated visual stimuli produce waves of activity in the visual cortex of freshwater turtles. Large-scale, biophysically realistic models of the visual cortex capture the basic features of the waves produced by single stimuli. However, these models do not respond to repetitive stimuli due to the presence of a long-lasting hyperpolarization that follows the initial wave.

Using systems biology to simplify complex disease: immune cartography.

What if there was a rapid, inexpensive, and accurate blood diagnostic that could determine which patients were infected, identify the organism(s) responsible, and identify patients who were not responding to therapy? We hypothesized that systems analysis of the transcriptional activity of circulating immune effector cells could be used to identify conserved elements in the host response to systemic inflammation, and furthermore, to discriminate between sterile and infectious etiologies. We review herein a validated, systems biology approach demonstrating that 1) abdominal and pulmonary sepsis diagnoses can be made in mouse models using microarray (RNA) data from circulating blood, 2) blood microarray data can be used to differentiate between the host response to Gram-negative and Gram-positive pneumonia, 3) the endotoxin response of normal human volunteers can be mapped at the level of gene expression, and 4) a similar strategy can be used in the critically ill to follow septic patients and quantitatively determine immune recovery. These findings provide the foundation of immune cartography and demonstrate the potential of this approach for rapidly diagnosing sepsis and identifying pathogens.

Arabidopsis transcriptome reveals control circuits regulating redox homeostasis and the role of an AP2 transcription factor.

Sensors and regulatory circuits that maintain redox homeostasis play a central role in adjusting plant metabolism and development to changing environmental conditions. We report here control networks in Arabidopsis (Arabidopsis thaliana) that respond to photosynthetic stress. We independently subjected Arabidopsis leaves to two commonly used photosystem II inhibitors: high light (HL) and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU).

The genome of Cyanothece 51142, a unicellular diazotrophic cyanobacterium important in the marine nitrogen cycle.

Unicellular cyanobacteria have recently been recognized for their contributions to nitrogen fixation in marine environments, a function previously thought to be filled mainly by filamentous cyanobacteria such as Trichodesmium. To begin a systems level analysis of the physiology of the unicellular N(2)-fixing microbes, we have sequenced to completion the genome of Cyanothece sp. ATCC 51142, the first such organism.

Integration of carbon and nitrogen metabolism with energy production is crucial to light acclimation in the cyanobacterium Synechocystis.

Light drives the production of chemical energy and reducing equivalents in photosynthetic organisms required for the assimilation of essential nutrients. This process also generates strong oxidants and reductants that can be damaging to the cellular processes, especially during absorption of excess excitation energy. Cyanobacteria, like other oxygenic photosynthetic organisms, respond to increases in the excitation energy, such as during exposure of cells to high light (HL) by the reduction of antenna size and photosystem content.

Plasticity of the systemic inflammatory response to acute infection during critical illness: development of the riboleukogram.

Background: Diagnosis of acute infection in the critically ill remains a challenge. We hypothesized that circulating leukocyte transcriptional profiles can be used to monitor the host response to and recovery from infection complicating critical illness.

Methodology/principal Findings: A translational research approach was employed.

Generation of the receptive fields of subpial cells in turtle visual cortex.

The visual cortex of turtles contains cells with at least two different receptive field properties. Superficial units are located immediately below the pial surface. They fire in response to moving bars located anywhere in binocular visual space and to two spots of light presented with different spatiotemporal separations.