Mapping Conformational Heterogeneity of Mitochondrial Nucleotide Transporter in Uninhibited States

One of the less well understood aspects of membrane transporters is the dynamic coupling between conformational change and substrate transport. NMR approaches are used herein to investigate conformational heterogeneity of the GTP/GDP carrier (GGC) from yeast mitochondria. NMR residual dipolar coupling (RDC) analysis of GGC in a DNA‐origami nanotube liquid crystal shows that several structured segments have different generalized degrees of order (GDO), thus indicating the presence of conformational heterogeneity. Complete GDO mapping reveals asymmetry between domains of the transporter and even within certain transmembrane helices. Nucleotide binding partially reduces local structural heterogeneity, and the substrate binds to multiple sites along the transport cavity. These observations suggest that mitochondrial carriers in the uninhibited states are intrinsically plastic and structural plasticity is asymmetrically distributed among the three homologous domains.     

Machine learning and signed particles,an alternative and efficient way to simulate quantum systems

Recently neural networks have been applied in the context of the signed particle formulation of quantum mechanics to rapidly and reliably compute the Wigner kernel of any provided potential. Important advantages were introduced, such as the reduction of the amount of memory required for the simulation of a quantum system by avoiding the storage of the kernel in a multi-dimensional array, as well as attainment of consistent speedup by the ability to realize the computation only on the cells occupied by signed particles. An inherent limitation was the number of hidden neurons to be equal to the number of cells of the discretized real space. In this work, anew network architecture is presented, decreasing the number of neurons in its hidden layer, thereby reducing the complexity of the network and achieving an additional speedup. The approach is validated on a onedimensional quantum system consisting of a Gaussian wave packet interacting with a potential barrier.     

Stable performance of an all-solid-state Li metal cell coupled with a high-voltage NCA cathode and ultra-high lithium content poly(ionic liquid)s-based polymer electrolyte

Journal of Solid State Electrochemistry - A poly(ionic liquid)s binder can provide stable performance of high-voltage composite cathodes based on lithium nickel cobalt aluminium oxide...     

Optical attenuation at the 1,550-nm wavelength in a reflective mode using electrochromic ruthenium complex film

Thin films of a dinuclear ruthenium complex have been prepared on a reflective electrode. The complex is redox-active in the near infrared spectral region. Electrochromic switching between the two oxidation states of the complex film gave 80% optical contrast at the telecommunication wavelength of 1,550 nm, which translates to an intrinsic attenuation of 17.5 dB/μm of the active material. Chronoamperometric study showed excellent stability over extended switching cycles as well as retaining high attenuation with a 5-s stepping time.     

The examination of a vignette activity sequence in a secondary mathematics methods course

Because of their brief nature, vignettes are a strategic way to highlight or explore complex instructional practices. Using a qualitative approach, we examined how the use of vignettes in a Vignette Activity Sequence contributed to secondary mathematics preservice teachers’ understanding of the Mathematical Practices and the Mathematics Teaching Practices. By examining three vignettes used in two iterations of a secondary mathematics methods course, the researchers found that preservice teachers were able to draw connections between the vignettes and their own teaching experiences. However, some misconceptions or incomplete understandings related to the practices were revealed. Preservice teachers sometimes provided vague evidence when identifying particular practices in the vignettes that did not clearly indicate if they understood the practices. Taken together, the researchers found the Vignette Activity Sequence to be a valuable formative assessment that could be used to inform instruction in a secondary mathematics methods course. These findings have implications for teacher preparation programs and mathematics teacher educators.     

A Laccase/Chitosan‐Lambda‐Carrageenan Based Voltammetric Biosensor for Phenolic Compound Detection

In this contribution, a new concept of voltammetric catechol biosensor, based on the encapsulation of laccase (LAC) in a chitosan+lambda‐carrageenan (CHIT+CAR) polyelectrolyte complex (PEC) employing a simple coacervation process is presented. Chitosan (CHIT) was prepared from α‐chitin extracted from shrimp shells and lambda‐carrageenan (CAR) was extracted from red algae, both polysaccharides and PEC being characterized using FTIR spectrometry and electrochemistry. Cyclic voltammetry was utilized to determine the analytical features of the laccase (LAC) biosensor for catechol detection. The linear range was from 10^?20 M to 10^?14 M with a sensitivity of 1.55 mA/p[catechol] and a limit of detection of 3×10^?21 M.The laccase biosensor exhibits good repeatability (RSD 2.38 %) and stability (four weeks). The developed biosensor was tested by applying it to the evaluation of the total polyphenolic content in natural oil samples.     

Family Business: Multiple Members of Major Phytohormone Classes Orchestrate Plant Stress Responses

Low‐molecular‐weight compounds such as jasmonic, abscisic and salicylic acids are commonly thought to be regulators of plant stress responses. However, it is becoming clear that these molecules, often referred to as phytohormones, are only a part of bigger groups of compounds with biological activity. We propose that the concept of “hormone families” may help to better understand plant physiological responses by taking into account not only the alleged main regulators, but also their precursors, conjugates and catabolites. Novel approaches to profile potentially active compounds in plants are discussed.     

Tailoring the resonances of nonlinear mechanical systems

Nonlinear Dynamics - The objective of this paper is the realization of a desired frequency–amplitude dependence of a specific vibration mode of a nonlinear system. To this end, we introduce...     

A low-memory algorithm for finding short product representations in finite groups

We describe a space-efficient algorithm for solving a generalization of the subset sum problem in a finite group G, using a Pollard-ρ approach. Given an element z and a sequence of elements S, our algorithm attempts to find a subsequence of S whose product in G is equal to z. For a random sequence S of length d log₂ n, where n = #G and d ≥ 2 is a constant, we find that its expected running time is O(?n log n){O(\sqrt{n}\,{\rm log}\,n)} group operations (we give a rigorous proof for d > 4), and it only needs to store O(1) group elements. We consider applications to class groups of imaginary quadratic fields, and to finding isogenies between elliptic curves over a finite field.     

Complex dynamics and targeted energy transfer in linear oscillators coupled to multi-degree-of-freedom essentially nonlinear attachments

We study the dynamics of a system of coupled linear oscillators with a multi-DOF end attachment with essential (nonlinearizable) stiffness nonlinearities. We show numerically that the multi-DOF attachment can passively absorb broadband energy from the linear system in a one-way, irreversible fashion, acting in essence as nonlinear energy sink (NES). Strong passive targeted energy transfer from the linear to the nonlinear subsystem is possible over wide frequency and energy ranges. In an effort to study the dynamics of the coupled system of oscillators, we study numerically and analytically the periodic orbits of the corresponding undamped and unforced hamiltonian system with asymptotics and reduction. We prove the existence of a family of countable infinity of periodic orbits that result from combined parametric and external resonance interactions of the masses of the NES. We numerically demonstrate that the topological structure of the periodic orbits in the frequency–energy plane of the hamiltonian system greatly influences the strength of targeted energy transfer in the damped system and, to a great extent, governs the overall transient damped dynamics. This work may be regarded as a contribution towards proving the efficacy the utilizing essentially nonlinear attachments as passive broadband boundary controllers. PACS numbers: 05.45.Xt, 02.30.Hq