Electronic conduction in a three-terminal molecular transistor

The electronic conduction of a novel, three-terminal molecular architecture, analogous to a heterojunction bipolar transistor is studied. In this architecture, two diode arms consisting of donor-acceptor molecular wires fuse through a ring, while a gate modulating wire is a \pi-conjugated wire. The calculated results show the enhancement or depletion mode of a transistor by applying a gate field along the positive or negative direction. A small gate field is required to switch on the current in the proposed architecture. The changes in the electronic conduction can be attributed to the intrinsic dipolar molecular architecture in terms of the evolution of molecular wavefunctions, specifically the one associated with the terphenyl group of the modulating wire in the presence of the gate field.Comment: 13 pages, 5 figure

Functionalized nanopore-embedded electrodes for rapid DNA sequencing

The determination of a patient's DNA sequence can, in principle, reveal an increased risk to fall ill with particular diseases [1,2] and help to design "personalized medicine" [3]. Moreover, statistical studies and comparison of genomes [4] of a large number of individuals are crucial for the analysis of mutations [5] and hereditary diseases, paving the way to preventive medicine [6]. DNA sequencing is, however, currently still a vastly time-consuming and very expensive task [4], consisting of pre-processing steps, the actual sequencing using the Sanger method, and post-processing in the form of data analysis [7]. Here we propose a new approach that relies on functionalized nanopore-embedded electrodes to achieve an unambiguous distinction of the four nucleic acid bases in the DNA sequencing process. This represents a significant improvement over previously studied designs [8,9] which cannot reliably distinguish all four bases of DNA. The transport properties of the setup investigated by us, employing state-of-the-art density functional theory together with the non-equilibrium Green's Function method, leads to current responses that differ by at least one order of magnitude for different bases and can thus provide a much more robust read-out of the base sequence. The implementation of our proposed setup could thus lead to a viable protocol for rapid DNA sequencing with significant consequences for the future of genome related research in particular and health care in general.Comment: 12 pages, 5 figure

Theoretical Study of Physisorption of Nucleobases on Boron Nitride Nanotubes: A New Class of Hybrid Nano-Bio Materials

We investigate the adsorption of the nucleic acid bases, adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U) on the outer wall of a high curvature semiconducting single-walled boron nitride nanotube (BNNT) by first principles density functional theory calculations. The calculated binding energy shows the order: G>A\approxC\approxT\approxU implying that the interaction strength of the (high-curvature) BNNT with the nucleobases, G being an exception, is nearly the same. A higher binding energy for the G-BNNT conjugate appears to result from a stronger hybridization of the molecular orbitals of G and BNNT, since the charge transfer involved in the physisorption process is insignificant. A smaller energy gap predicted for the G-BNNT conjugate relative to that of the pristine BNNT may be useful in application of this class of biofunctional materials to the design of the next generation sensing devices.Comment: 17 pages 6 figure

Divine Delight and the Little Way: A Renewal Strategy at Our Savior\u27s Church

The purpose of this doctoral project is to renew the mission of Our Savior’s Church. This was accomplished through teaching the loving kindness meditation and the little way of St. Thérèse of Lisieux. A retreat introduced these two spiritual practices as a way to enhance the congregation’s mission. Part One details the setting of Our Savior’s Lutheran. After constant pastoral turnover for the past seven years, Our Savior’s lost its energy. Our Savior’s discerned a new mission statement in 2019 as a caring community called by Christ to live and serve in faith. Learning new spiritual practices including the loving kindness meditation and the little way, of St. Thérèse of Lisieux, provided a framework to live into this new mission. Part Two describes the fruit of contemplation practices with the little way. Delighting in God through prayer and contemplation enables one to embrace others authentically. Experiencing God’s love directly through contemplative practices increases the capacity to extend hospitality. St. Thérèse of Lisieux is an example of this life of discipleship. St. Thérèse saw herself, and all of humanity, as unique souls belonging in God’s garden, all created in the image of God. From this anchoring in her identity as a child of God, St. Thérèse abundantly shared divine love through the little way. Part Three relays the implications of transforming an environment through the daily implementation of the little way as a spiritual practice. In a retreat setting, active members of Our Savior’s engaged in spiritual practices including St. Thérèse’s model of compassion. After experiencing the little way in this retreat, participants were commissioned to practice this as a spiritual discipline and the loving kindness meditation for forty days. Assessments determined that the little way offered congregational renewal and equipped Our Savior’s members to renew in mission

Physisorption of Nucleobases on Graphene

We report the results of our first-principles investigation on the interaction of the nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) with graphene, carried out within the density functional theory framework, with additional calculations utilizing Hartree--Fock plus second-order Moeller-Plesset perturbation theory. The calculated binding energy of the nucleobases shows the following hierarchy: G > T ~ C ~ A > U, with the equilibrium configuration being very similar for all five of them. Our results clearly demonstrate that the nucleobases exhibit significantly different interaction strengths when physisorbed on graphene. The stabilizing factor in the interaction between the base molecule and graphene sheet is dominated by the molecular polarizability that allows a weakly attractive dispersion force to be induced between them. The present study represents a significant step towards a first-principles understanding of how the base sequence of DNA can affect its interaction with carbon nanotubes, as observed experimentally.Comment: 7 pages, 3 figure

Ab initio linear scaling response theory: Electric polarizability by perturbed projection

A linear scaling method for calculation of the static {\em ab inito} response within self-consistent field theory is developed and applied to calculation of the static electric polarizability. The method is based on density matrix perturbation theory [Niklasson and Challacombe, cond-mat/0311591], obtaining response functions directly via a perturbative approach to spectral projection. The accuracy and efficiency of the linear scaling method is demonstrated for a series of three-dimensional water clusters at the RHF/6-31G** level of theory. Locality of the response under a global electric field perturbation is numerically demonstrated by approximate exponential decay of derivative density matrix elements.Comment: 4.25 pages in PRL format, 2 figure

Performance of coconut (Cocos nucifera L.) hybrids for yield and quality in the Utkal plain region of Odisha state, India

Cocos nucifera L. is a perennial oil yielding crop with a long productive life span (>60 years); thus, identifying a suitable high yielding hybrid to a particular agro-climatic region plays a prime role in achieving sustainable coconut yield. In this context, an evaluation trial with varietal cross combinations involving Tall × Dwarf (six crosses) and Dwarf × Tall (two crosses) was conducted at All India Coordinated Research Project (AICRP) on Palms, Bhubaneshwar Centre, Odisha, for 15 years. The experiment was laid out in randomized block design with four replications maintaining six palms per replication. Observations on yield and yield attributing characters during 2018 to 2020 revealed the superior performance of ECT × GBGD (99.1 nuts), which was followed by ECT × MYD (86.9 nuts) over the local check (ECT) by recording higher nut yield. Copra output per palm was significantly the highest under ECT × GBGD (20.6 kg palm-1), followed by LCT × COD (18.6 kg palm-1). Hybrids possessed a higher quantity of organoleptically ‘good’ tender nut water (270.3 to 354.1 mL) with TSS of 5.8 to 6.9 °Brix, 25.4 to 34.0 ppm of sodium and 2065.9 to 2885.0 ppm of potassium

Förster Resonance Energy Transfer between Core/Shell Quantum Dots and Bacteriorhodopsin

An energy transfer relationship between core-shell CdSe/ZnS quantum dots (QDs) and the optical protein bacteriorhodopsin (bR) is shown, demonstrating a distance-dependent energy transfer with 88.2% and 51.1% of the QD energy being transferred to the bR monomer at separation distances of 3.5 nm and 8.5 nm, respectively. Fluorescence lifetime measurements isolate nonradiative energy transfer, other than optical absorptive mechanisms, with the effective QD excited state lifetime reducing from 18.0 ns to 13.3 ns with bR integration, demonstrating the Förster resonance energy transfer contributes to 26.1% of the transferred QD energy at the 3.5 nm separation distance. The established direct energy transfer mechanism holds the potential to enhance the bR spectral range and sensitivity of energies that the protein can utilize, increasing its subsequent photocurrent generation, a significant potential expansion of the applicability of bR in solar cell, biosensing, biocomputing, optoelectronic, and imaging technologies