Dynamic hydration valve controlled ion permeability and stability of NaK channel

The K^+^, Na^+^, Ca^2+^ channels are essential to neural signalling, but our current knowledge at atomic level is mainly limited to that of K^+^ channels. Unlike a K^+^ channel having four equivalent K^+^-binding sites in its selectivity filter, a NaK channel conducting both Na^+^ and K^+^ ions has a vestibule in the middle part of its selectivity filter, in which ions can diffuse but not bind specifically. However, how the NaK channel conducts ions remains elusive. Here we find four water grottos connecting with the vestibule of the NaK selectivity filter. Molecular dynamics and free energy calculations show that water molecules moving in the vestibule-grotto complex hydrate and stabilize ions in the filter and serve as a valve in conveying ions through the vestibule for controllable ion permeating. During ion conducting, the water molecules are confined within the valve to guarantee structure stability. The efficient exquisite hydration valve should exist and play similar roles in the large family of cyclic nucleotide-gated channels which have similar selectivity filter sequences. The exquisite hydration valve mechanism may shed new light on the importance of water in neural signalling

Self-Aligned Ballistic Molecular Transistors and Electrically Parallel Nanotube Arrays

Carbon nanotube field-effect transistors with structures and properties near the scaling limit with short (down to 50 nm) channels, self aligned geometries, palladium electrodes with low contact resistance and high-k dielectric gate insulators are realized. Electrical transport in these miniature transistors is near ballistic up to high biases at both room and low temperatures. Atomic layer deposited (ALD) high-k films interact with nanotube sidewalls via van der Waals interactions without causing weak localization at 4 K. New fundamental understanding of ballistic transport, optical phonon scattering and potential interfacial scattering mechanisms in nanotubes are obtained.Comment: Nano Letters, in pres

Combinatorial interpretations of two identities of Guo and Yang

The restricted partitions in which the largest part is less than or equal to $N$ and the number of parts is less than or equal to $k$ were investigated by Andrews. These partitions were extended recently by the author to partitions into parts of two kinds. In this paper, we use a new class of restricted partitions into parts of two kinds to provide new combinatorial interpretations for two identities of Guo and Yang

McCarthy\u27s The Road and Ethical Choice in a Post-Apocalyptic World

In her article McCarthy\u27s The Road and Ethical Choice in a Post-Apocalyptic World Jingjing Guo analyses ethical choice and its implications in McCarthy\u27s The Road. After examining the deterioration of the ethical context and the prevalence of evil reflected in cannibalism, Guo highlights the father\u27s ethical choice and dilemma. Different from most others, the father chooses to keep alive to protect his son, and to stay man and stay good in a physically devastated and morally bankrupted world. Through discussing the meaning of the metaphor fire and carrying the fire, Guo further explores the significance of the father\u27s choice in passing the fire of human race to a new world

First measurement of the K−n →Λπ−non-resonant transition amplitude below threshold

We present the analysis of K−absorption processes on He4 leading to Λπ−final states, measured with the KLOE spectrometer at the DAΦNE e+e−collider and extract, for the first time, the modulus of the non-resonant K−n →Λπ−direct production amplitude about 33 MeV below the K‾N threshold. This analysis also allows to disentangle the K−nuclear absorption at-rest from the in-flight capture, for K−momenta of about 120 MeV. The data are interpreted with the help of a phenomenological model, and the modulus of the non-resonant K−n →Λπ−amplitude for K−absorption at-rest is found to be |AK−n→Λπ−|=(0.334±0.018stat−0.058+0.034syst)fm

Wavelength tuneable pulse monitoring using a Two-Photon-Absorption microcavity

Two Photon Absorption (TPA) is a non-linear optical-to-electrical conversion process that can be significantly enhanced by placing the active region within a resonance microcavity. The experiment confirmed the potential use of the microcavity structure for monitoring a single channel in multi-wavelength systems. The cavity can be designed for different applications depending on desired resonance width or cavity life time allowing the contrast ratio to be further improved. Due to the possibility of tuning the resonance wavelength by cavity tilting, a single device can be used to monitor a number of WDM channels without the need for additional optical filters

Synthesis and evaluation of N⁶-substituted apioadenosines as potential adenosine A₃ receptor modulators

Adenosine receptors (ARs) trigger signal transduction pathways inside the cell when activated by extracellular adenosine. Selective modulation of the A(3)AR subtype may be beneficial in controlling diseases such as colorectal cancer and rheumatoid arthritis. Here, we report the synthesis and evaluation of beta-D-apio-D-furano- and alpha-D-apio-L-furanoadenosines and derivatives thereof. Introduction of a 2-methoxy-5-chlorobenzyl group at N-6 of beta-D-apio-D-furanoadenosine afforded an A(3)AR antagonist (10c, K = 0.98 mu M), while a similar modification of an alpha-D-apio-L-furanoadenosine gave rise to a partial agonist (11c, K-i = 3.07 mu M). The structural basis for this difference was examined by docking to an A(3)AR model; the antagonist lacked a crucial interaction with Thr94

A ThDP-dependent enzymatic carboligation reaction involved in Neocarazostatin A tricyclic carbazole formation

Acknowledgements This work was supported by grants from the National Natural Science Foundation of China (31570033 to Y. Y.) and the Leverhulme Trust-Royal Society Africa Award (AA090088 to K. K and H. D.). Open access via RSC Gold 4 Gold.Peer reviewedPublisher PD

Proof of some congruence conjectures of Z.-H. Sun involving Ap\'{e}ry-like numbers

In this paper, we mainly prove the following conjecture of Z.-H. Sun cite{SH20}: Let $p>3$ be a prime. Then $$\sum_{k=0}^{p-1}\binom{2k}k\frac{3k+1}{(-16)^k}f_k\equiv(-1)^{(p-1)/2}p+p^3E_{p-3}\pmod{p^4},$$ where $f_n=\sum_{k=0}^n\binom{n}k^3$ and $E_n$ stand for the $n$th Franel number and $n$th Euler number respectively.Comment: 11 page