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Voltage-gated calcium channels control key functions of excitable cells, like synaptic transmission in neurons and the contraction of heart and skeletal muscles. To accomplish such diverse functions, different calcium channels activate at different voltages and with distinct kinetics. To identify the molecular mechanisms governing specific voltage sensing properties, we combined structure modeling, mutagenesis, and electrophysiology to analyze the structures, free energy, and transition kinetics of the activated and resting states of two functionally distinct voltage sensing domains (VSDs) of the eukaryotic calcium channel Ca V 1.1. Both VSDs displayed the typical features of the sliding helix model; however, they greatly differed in ion-pair formation of the outer gating charges. Specifically, stabilization of the activated state enhanced the voltage dependence of activation, while stabilization of resting states slowed the kinetics. This mechanism provides a mechanistic model explaining how specific ion-pair formation in separate VSDs can realize the characteristic gating properties of voltage-gated cation channels. Communication in our body runs on electricity. Between the exterior and interior of every living cell, there is a difference in electrical charge, or voltage. Rapid changes in this so-called membrane potential activate vital biological processes, ranging from muscle contraction to communication between nerve cells. Ion channels are cellular structures that maintain membrane potential and help ‘excitable’ cells like nerve and muscle cells produce electrical impulses. They are specialized proteins that form highly specific conduction pores in the cell surface. When open, these channels let charged particles (such as calcium ions) through, rapidly altering the electrical potential between the inside and outside the cell. To ensure proper control over this process, most ion channels open in response to specific stimuli, which is known as ‘gating’. For example, voltage-gated calcium channels contain charge-sensing domains that change shape and allow the channel to open once the membrane potential reaches a certain threshold. These channels play important roles in many tissues and, when mutated, can cause severe brain or muscle disease. Although the basic principle of voltage gating is well-known, the properties of individual voltage-gated calcium channels still vary. Different family members open at different voltage levels and at different speeds. Such fine-tuning is thought to be key to their diverse roles in various parts of the body, but the underlying mechanisms are still poorly understood. Here, Fernández-Quintero, El Ghaleb et al. set out to determine how this variation is achieved. The first step was to create a dynamic computer simulation showing the detailed structure of a mammalian voltage-gated calcium channel, called Ca V 1.1. The simulation was then used to predict the movements of the voltage sensing regions while the channel opened. The computer modelling experiments showed that although the voltage sensors looked superficially similar, they acted differently. The first of the four voltage sensors of the studied calcium channel controlled opening speed. This was driven by shifts in its configuration that caused oppositely charged parts of the protein to sequentially form and break molecular bonds; a process that takes time. In contrast, the fourth sensor, which set the voltage threshold at which the channel opened, did not form these sequential bonds and accordingly reacted fast. Experimental tests in muscle cells that had been engineered to produce channels with mutations in the sensors, confirmed these results. These findings shed new light on the molecular mechanisms that shape the activity of voltage-gated calcium channels. This knowledge will help us understand better how ion channels work, both in healthy tissue and in human disease.

Organic fluorescent materials have been an integral part of recently emerged optoelectronic device technologies owing to their good photophysical properties such as high quantum yields and significant photostability. In particular, switchable and tunable solid‐state fluorescence has attracted increasing attention in recent years both in the field of fundamental research and industrial applications. Unlike in solution, fluorescence in the solid state is a collective phenomenon of molecules that are commonly modulated through controlling molecular packing and the electronic conjugation of fluorophores. Several strategies, including chemical modification, have been developed to alter the fluorophore molecular arrangement in the solid state. This Review article describes the various strategies that have been effectively utilised to achieve switchable and tunable fluorescence in the organic solid state. Give us a tune! Switching and tuning photophysical properties, particularly the solid‐state fluorescence of small organic molecules, has attracted great attention owing to the recent emergence of optoelectronic technologies. The strategies (see figure) that have been used effectively to modify the solid‐state fluorescence properties are discussed in this Review.

Follies in America examines historicized garden buildings, known as \"follies,\" from the nation's founding through the American centennial celebration in 1876. In a period of increasing nationalism, follies-such as temples, summerhouses, towers, and ruins-brought a range of European architectural styles to the United States. By imprinting the land with symbols of European culture, landscape gardeners brought their idea of civilization to the American wilderness. Kerry Dean Carso's interdisciplinary approach in Follies in America examines both buildings and their counterparts in literature and art, demonstrating that follies provide a window into major themes in nineteenth-century American culture, including tensions between Jeffersonian agrarianism and urban life, the ascendancy of middle-class tourism, and gentility and social class aspirations.

\"Posits an alternative understanding of the relationship between the state and social elites in the middle period of Chinese imperial history. The book shows in vivid detail how state power and local elite interests were mutually constitutive and reinforcing\"--Provided by the publisher.

Reported is the synthesis of 3D hierarchical structures based on one‐dimensional MnO2 nanobuilding blocks (nanorods, nanowires, and nanoneedles) by means of a facile and scalable coprecipitation method and their use as electrodes for the assembly of all‐solid‐state supercapacitors. Asymmetric devices were also assembled by using these nanostructured MnO2 materials as the positive electrode and reduced graphene oxide (rGO) as the negative electrode with a polymeric gel electrolyte. The asymmetric cells successfully extend the working voltage windows beyond 1.4 V and allowed for a maximum voltage of 1.8 V. An asymmetric device based on hierarchical nanoneedle‐like MnO2 and rGO achieved a maximum specific capacitance of 99 F g−1 at a scan rate of 10 mV s−1 with a stable operational voltage of 1.8 V. This high value allowed for a large specific energy of 24.12 Wh kg−1. New builders on the block: The synthesis of 3D hierarchical structures based on 1D MnO2 nanobuilding blocks by means of a facile and scalable coprecipitation method and their use as electrodes for the assembly of all‐solid‐state supercapacitors is described. The figure show an example of an asymmetric device based on hierarchical nanoneedle (Nn)‐like MnO2 and reduced graphene oxide.

The unique electronic properties of the surface electrons in a topological insulator are protected by time-reversal symmetry. Circularly polarized light naturally breaks time-reversal symmetry, which may lead to an exotic surface quantum Hall state. Using time-and angle-resolved photoemission spectroscopy, we show that an intense ultrashort midinfrared pulse with energy below the bulk band gap hybridizes with the surface Dirac fermions of a topological insulator to form Floquet-Bloch bands. These photon-dressed surface bands exhibit polarization-dependent band gaps at avoided crossings. Circularly polarized photons induce an additional gap at the Dirac point, which is a signature of broken time-reversal symmetry on the surface. These observations establish the Floquet-Bloch bands in solids and pave the way for optical manipulation of topological quantum states of matter.

Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.