Dependency of Cellular Decision Making in Physiology and Influence of Preceding Growth Conditions

Events from the past growth conditions influence the course of physiology, and it gets reflected in the present cell behaviour. During this process, cells acquire a metabolic option which carries signature of the past, and it dictates the performance in the present situation. Study uses Escherichia coli as a sample organism wherein three scenarios of preceding growth conditions were created with varying nutritional status and pre-treatment strategies. This exercise leads to different seed cultures, which were subjected to growth using the four different substrates. The different seed culture behaviours were analysed by observing the respirometric rate of the seed culture and were followed by growth dynamics with different substrates. These two data sets were independently analysed by three-way ANOVA to arrive at strategic coupling of programming conditions to relate the available (respirometric rates) and executable physiology (growth kinetics).     

Dipolar solvation dynamics in room temperature ionic liquids: an effective medium calculation using dielectric relaxation data

Solvation dynamics in four imidazolium cation based room temperature ionic liquids (RTIL) have been calculated by using the recently measured dielectric relaxation data [ J. Phys. Chem. B 2008, 112, 4854 ] as an input in a molecular hydrodynamic theory developed earlier for studying solvation energy relaxation in polar solvents. Coumarin 153 (C153), 4-aminophthalimide (4-AP), and trans-4-dimethylamino-4'-cyanostilbene (DCS) have been used as probe molecules for this purpose. The medium response to a laser-excited probe molecule in an ionic liquid is approximated by that in an effective dipolar medium. The calculated decays of the solvent response function for these RTILs have been found to be biphasic and the decay time constants agree well with the available experimental and computer simulation results. Also, no probe dependence has been found for the average solvation times in these ionic liquids. In addition, dipolar solvation dynamics have been predicted for two other RTILs for which experimental results are not available yet. These predictions should be tested against experiments and/or simulation studies.     

Metal/metal sulfide functionalized single-walled carbon nanotubes: FTO-free counter electrodes for dye sensitized solar cells

The use of single-walled carbon nanotubes (CNT) thin films to replace conventional fluorine-doped tin oxide (FTO) and both FTO and platinum (Pt) as the counter electrode in dye sensitized solar cells (DSSC) requires surface modification due to high sheet resistance and charge transfer resistance. In this paper, we report a simple, solution-based method of preparing FTO-free counter electrodes based on metal (Pt) or metal sulfide (Co(8.4)S(8), Ni(3)S(2)) nanoparticles/CNT composite films to improve device performance. Based on electrochemical studies, the relative catalytic activity of the composite films was Pt > Co(8.4)S(8) > Ni(3)S(2). We achieved a maximum efficiency of 3.76% for the device with an FTO-free counter electrode (Pt/CNT). The device with an FTO- and Pt-free (CoS/CNT) counter electrode gives 3.13% efficiency.     

Calculation of transition dipole moment in fluorescent proteins--towards efficient energy transfer

F?rster Resonance Energy Transfer (FRET) between fluorescent proteins (FPs) is widely used to construct fluorescent sensor proteins, to study intracellular protein-protein interactions and to monitor conformational changes in multidomain proteins. Although FRET depends strongly on the orientation of the transition dipole moments (TDMs) of the donor and acceptor fluorophores, this orientation dependence is currently not taken into account in FRET sensor design. Similarly, studies that use FRET to derive structural constrains typically assume a κ(2) of 2/3 or use the TDM of green fluorescent protein, as this is the only FP for which the TDM has been determined experimentally. Here we used time-dependent density functional theory (TD-DFT) methods to calculate the TDM for a comprehensive list of commonly used fluorescent proteins. The method was validated against higher levels of calculation. Validation with model compounds and the experimentally determined TDM of GFP shows that the TDM is mostly determined by the structure of the π-conjugated fluorophore and is insensitive to non-conjugated side chains or the protein surrounding. Our calculations not only provide TDM for most of the currently used FPs, but also suggest an empirical rule that can be used to obtain the TDMs for newly developed fluorescent proteins in the future.     

The role of bioactive compounds on the promotion of neurite outgrowth

Neurite loss is one of the cardinal features of neuronal injury. Apart from neuroprotection, reorganization of the lost neuronal network in the injured brain is necessary for the restoration of normal physiological functions. Neuritogenic activity of endogenous molecules in the brain such as nerve growth factor is well documented and supported by scientific studies which show innumerable compounds having neurite outgrowth activity from natural sources. Since the damaged brain lacks the reconstructive capacity, more efforts in research are focused on the identification of compounds that promote the reformation of neuronal networks. An abundancy of natural resources along with the corresponding activity profiles have shown promising results in the field of neuroscience. Recently, importance has also been placed on understanding neurite formation by natural products in relation to neuronal injury. Arrays of natural herbal products having plentiful active constituents have been found to enhance neurite outgrowth. They act synergistically with neurotrophic factors to promote neuritogenesis in the diseased brain. Therefore use of natural products for neuroregeneration provides new insights in drug development for treating neuronal injury. In this study, various compounds from natural sources with potential neurite outgrowth activity are reviewed in experimental models.     

Common fixed point theorems for four mappings through generalized altering distances in ordered metric spaces

Using the concepts introduced by Abbas et?al. (Appl Math Lett 24:1520?C1526, 2011), the purpose of this paper is to establish coincidence point and common fixed point results for four maps satisfying generalized weak contractions under generalized altering distance functions in ordered complete metric spaces.     

Synthesis and characterization of amphiphilic and hydrophobic ABA-type tri-block copolymers using telechelic polyurethane as atom transfer radical polymerization macroinitiator

Atom transfer radical polymerization of 2-(dimethylamino) ethylmethacrylate and styrene was carried out using tertiary bromine-terminated telechelic polyurethane as a macroinitiator. The resulting ABA-type amphiphilic, poly (2-(dimethylamino) ethylmethacrylate)-b-polyurethane-b-poly (2-(dimethylamino) ethylmethacrylate) and hydrophobic, polystyrene-b-polyurethane-b-polystyrene tri-block copolymers were characterized by spectral, thermal, and chromatographic techniques. As the conversion increases, [`(M)]<sub>\textn</sub> {\overline M_{_{\text{n}}}} also increases linearly. Theoretical M <sub>n</sub> values of the tri-block copolymers were comparable with the experimental [`(M)]_\textn {\overline M_{_{\text{n}}}} values. These results show that the polymerization of styrene and 2-(dimethylamino) ethylmethacrylate occurred through controlled radical polymerization mechanism. Mole percentage of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers was calculated using proton nuclear magnetic resonance spectroscopy, and the results were comparable with the gel permeation chromatography results. The glass transition temperatures of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers appeared at 72 °C and 110 °C, respectively. These results confirm the presence of two phases in the tri-block copolymers.     

Microstructures of Choline Amino Acid based Biocompatible Ionic Liquids

Bio-compatible ionic liquids (Bio-ILs) represent a class of solvents with peculiar properties and exhibit huge potential for their applications in different fields of chemistry. Ever since they were discovered, researchers have used bio-ILs in diverse fields such as biomass dissolution, CO₂ sequestration, and biodegradation of pesticides. This review highlights the ongoing research studies focused on elucidating the microscopic structure of bio-ILs based on cholinium cation ([Ch]⁺) and amino acid ([AA]⁻) anions using the state-of-the-art and classical molecular dynamics (MD) simulations. The microscopic structure associated with these green ILs guides their suitability for specific applications. ILs of this class differ in the side chain of the amino acid anions, and varying the side chain significantly affects the structure of these ILs and thus helps in tuning the efficiency of biomass dissolution. This review demonstrates the central role of the side chain on the morphology of choline amino acid ([Ch][AA]) bio-ILs. The seemingly matured field of bio-ILs and their employment in various applications still holds significant potential, and the insights on their microscopic structure would steer the field of target specific application of these green ILs.