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Ruthenium(II) Metalla2catenanes and Macrocycles via Donor-Dependent Self-Assembly
No full textDonor-selective coordination-driven self-assembly of a bis(dipyrrin)-bridged new diruthenium acceptor (RuA) with dipyridyl and diimidazolyl donors has been reported. The self-assembly of the ruthenium(II) acceptor with imidazolyl donors resulted in the formation of either 2 + 2 self-assembled monomeric macrocycles (MMs) or a mixture of metalla2catenanes (MCs) and MMs depending on the solvents used. On the contrary, similar self-assembly with the pyridyl donors resulted in simple 2 + 2 macrocycles (MMs) exclusively, irrespective of the solvents used. The new ruthenium acceptor and self-assembled macrocycles were systematically characterized by multinuclear NMR and electrospray ionization mass spectrometry study. The structure of one of the metalla2catenanes (MC1) was further confirmed by single-crystal X-ray diffraction studies. Density functional theory calculations inferred that the interlocked structures with imidazolyl donors are stabilized by �-� interactions between the benzene rings, while such interactions cease to exist with the pyridyl linkers, leading to the formation of noninterlocked macrocycles. © 2019 American Chemical Society
Cationic distribution, exchange interactions, and relaxation dynamics in Zn-diluted MnCo 2 O 4 nanostructures
No full textWe report an experimental investigation of the electronic structure and magnetic properties of bulk and nanosized MnCo 2 O 4 diluted with Zn. The cationic distribution for tetrahedral A-site dilution is (Co 1-y A2 +Zn yA 2+ ) A Mn 3+ Co 3+ B O 4 ± δ, whereas B-site dilution results in (Co 2+ ) A Mn 1-xB 3+ Zn xB 2+ Co 3+ B O 4-δ . The strength of exchange interaction J ij between the magnetic ions in a bulk spinel lattice decreases by � 15 % for A-site dilution relative to the undiluted compound; however, B-site dilution results in an enhancement in J ij by 17%. The frequency and temperature dependence of dynamic-susceptibility � ac (f,T) studies of nanostructured compounds reveals the existence of spin-glass like behavior below the freezing temperature T F � 125.7K (for x B = 0.2) and 154.3 K (y A = 0.1). Relaxation time � follows the Power-Law variation with a dynamical critical exponent z ν = 6.17 and microscopic spin relaxation time � 0 = 4.4 � 10 -15 s for x B = 0.2 (for y A = 0.1, z ν = 5.2 and � o = 5.4 � 10 -13 s ). The amplitude and peak position in � ac (T) decreases with an increase in the DC bias field, which indicates that the spin-glass phase can survive in the presence of low fields forming a critical line with an exponent 2/3. This behavior is similar to the de Almeida-Thouless (AT-line) analysis in the T-H phase diagram which supports the existence of spin-glass like behavior below T F in these Zn diluted spinels. © 2019 Author(s)
Cleaning carbohydrate impurities from lignin using Pseudomonas fluorescens
No full textA novel method of cleaning waste lignin biomass by means of selective biodegradation of cellulose and hemicellulose is investigated. This method uses Pseudomonas fluorescens (P. fluorescens), a non-pathogenic bacterium capable of producing cellulolytic enzymes, cleaving polymeric carbohydrates into free sugars and utilizing them as their carbon source. The growth of P. fluorescens on lignin biomass was confirmed by increasing cell count with time and visualized by scanning electron microscopy (SEM). Depletion of free sugars in the growth medium was measured by Technical Association of the Pulp and Paper Industry (TAPPI) methods and by time-of-flight secondary ion mass spectrometry (ToF SIMS), which showed a significant decrease in the carbohydrate content and an increase in the lignin fraction after P. fluorescens biodegradation. The molar mass distribution of lignin before and after the biodegradation of carbohydrate impurities showed no indication of lignin depolymerization. Our results strongly support the biodegradation of carbohydrate impurities from waste lignin by P. fluorescens as an effective, green and eco-friendly process
Variation of gene expression in plants is influenced by gene architecture and structural properties of promoters
No full textIn higher eukaryotes, gene architecture and structural properties of promoters have emerged as significant factors influencing variation in number of transcripts (expression level) and specificity of gene expression in a tissue (expression breadth), which eventually shape the phenotype. In this study, transcriptome data of different tissue types at various developmental stages of A. thaliana, O. sativa, S. bicolor and Z. mays have been used to understand the relationship between properties of gene components and its expression. Our findings indicate that in plants, among all gene architecture and structural properties of promoters, compactness of genes in terms of intron content is significantly linked to gene expression level and breadth, whereas in human an exactly opposite scenario is seen. In plants, for the first time we have carried out a quantitative estimation of effect of a particular trait on expression level and breadth, by using multiple regression analysis and it confirms that intron content of primary transcript (as ) is a powerful determinant of expression breadth. Similarly, further regression analysis revealed that among structural properties of the promoters, stability is negatively linked to expression breadth, while DNase1 sensitivity strongly governs gene expression breadth in monocots and gene expression level in dicots. In addition, promoter regions of tissue specific genes are found to be enriched with TATA box and Y-patch motifs. Finally, multi copy orthologous genes in plants are found to be longer, highly regulated and tissue specific. This is an open access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication
Polymer composite of poly (vinylidene fluoride)-2-methyl-4-nitroaniline via hot-pressing technique; structural, optical and electrical properties
No full textSemitransparent (45% transparency at 1 mu m) composites comprising poly (vinylidene fluoride) PVDF] and 2-methyl-4-nitroaniline MNA] were fabricated by home-built hot-pressing technique. The composite nature of thus fabricated samples was confirmed via x-ray powder diffraction (XRD) studies. Formation of beta-phase (2 theta similar to 20.7 (200)) was observed in the hot-pressed PVDF-MNA composites through XRD data. Scanning Electron Microscopy (SEM) carried out on these samples revealed the presence of platy and rod shaped features of individual crystallite of MNA (nearly 5-20 mu m) embedded in the PVDF matrix. Optical transmission for 10 wt% MNA in PVDF was found to be around 40% (uncorrected for the reflection/scattering losses) at 446 nm and has higher towards longer wavelengths. The second harmonic generation (SHG) studies confirmed an increase in intensity with an increase in weight percentage of MNA in PVDF. Room temperature dielectric constant and dielectric loss measurements were conducted on the hot-pressed PVDF and composites of PVDF and MNA as a function of frequency (100 Hz-100 MHz). The polarization versus electric field (Hysteresis loop) behaviour of hot-pressed PVDF and composites of MNA and PVDF was also investigated. The remnant polarization (2P(r) = 0.246 mu C/cm(2)) was observed the semitransparent hot-pressed composite (10 wt% MNA in PVDF)
Evaporating spray characteristics of a diesel-ethanol micro-emulsion
No full textIn the present study, evaporating spray characteristics of a diesel-ethanol micro-emulsion are reported for the first time under realistic engine-like conditions. A diesel-ethanol emulsion has been prepared by using 60% diesel, 20% anhydrous ethanol and 20% JME as an emulsifier. The evaporating spray characteristics in terms of liquid penetration, vapour penetration, liquid length and spread angle have been measured for the emulsion and compared with those of diesel. A high-pressure chamber with optical access is used in the present study for spray characterization. The chamber is filled with nitrogen which is heated to reach a final experimental condition of 50-bar pressure and 900-K temperature. A custom-made single-hole nozzle with a hole size of 190-mu m has been used for the study. Surprisingly, the results have shown that the liquid penetration and the vapour penetration of the emulsion match closely with those of diesel showing no influence of droplet micro-explosion on spray characteristics. It is surmised that the enhanced rate of evaporation is compensated by evaporative cooling of low boiling point fuel and higher boiling point of JME leading to similar liquid length for the emulsion and diesel
Modified fermi level in strontium nanoparticles decorated reduced graphene oxide for wide concentration detection of nitrogen dioxide at room temperature
No full textWe demonstrate room temperature nitrogen dioxide (NO2) sensing at parts per billion level (ppb) using a chemiresistive sensor based on strontium nanoparticles decorated reduced graphene oxide. Among the various functional materials used for NO2 sensing, it is a unique study reported for the first time using hybrid of reduced graphene oxide with a low work function alkaline earth metal. An increase of nearly 222% in sensing response is observed in the hybrid device over reduced graphene oxide alone at a concentration of 1 ppm. Moreover, the hybrid device exhibits a good sensitivity to NO2 over a wide concentration range from 500 ppb to 104 ppm. Additionally, the hybrid device is highly selective to NO2 amongst other pollutants. The integration of strontium nanoparticles onto reduced graphene oxide imparts excellent performance to the hybrid sensor due to their high adsorption energy for NO2. Further, strontium nanoparticle, being a low work function material, raises the fermi level of reduced graphene oxide and populate it with more electrons thus facilitating rapid charge transfer to electrophilic nitrogen dioxide. Hence, strontium nanoparticles attribute to an important role in fast and selective adsorption of nitrogen dioxide at room temperature with underlying graphene helping in rapid charge transfer
Search for supersymmetric partners of electrons and muons in proton-proton collisions at root s=13 TeV
No full textA search for direct production of the supersymmetric (SUSY) partners of electrons or muons is presented in final states with two opposite-charge, same-flavour leptons (electrons and muons), no jets, and large missing transverse momentum. The data sample corresponds to an integrated luminosity of 35.9 fb(-1) of proton-proton collisions at root s = 13 TeV, collected with the CMS detector at the LHC in 2016. The search uses the M-T2 variable, which generalises the transverse mass for systems with two invisible objects and provides a discrimination against standard model backgrounds containing W bosons. The observed yields are consistent with the expectations from the standard model. The search is interpreted in the context of simplified SUSY models and probes slepton masses up to approximately 290, 400, and 450 GeV, assuming right-handed only, left-handed only, and both right- and left-handed sleptons (mass degenerate selectrons and smuons), and a massless lightest supersymmetric particle. Limits are also set on selectrons and smuons separately. These limits show an improvement on the existing limits of approximately 150GeV. (C) 2019 The Author(s). Published by Elsevier B.V
Observation of Single Top Quark Production in Association with a Z Boson in Proton-Proton Collisions at root s=13 TeV
No full textThe observation of single top quark production in association with a Z boson and a quark (tZq) is reported. Events from proton-proton collisions at a center-of-mass energy of 13 TeV containing three charged leptons (either electrons or muons) and at least two jets are analyzed. The data were collected with the CMS detector in 2016 and 2017 and correspond to an integrated luminosity of 77.4fb(-1). The increased integrated luminosity, a multivariate lepton identification, and a redesigned analysis strategy improve significantly the sensitivity of the analysis compared to previous searches for tZq production. The tZq signal is observed with a significance well over 5 standard deviations. The measured tZq production cross section is sigma(pp -> tZq -> tl(+) l(-) q) = 111 +/- 13 (stat)(-9)(+11) (syst) fb, for dilepton invariant masses above 30 GeV, in agreement with the standard model expectation