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Accounts of Chemical Research

Andres Canales, Seongjun Park, Antje Kilias, Polina Anikeeva
Multifunctional devices for modulation and probing of neuronal activity during free behavior facilitate studies of functions and pathologies of the nervous system. Probes composed of stiff materials, such as metals and semiconductors, exhibit elastic and chemical mismatch with the neural tissue, which is hypothesized to contribute to sustained tissue damage and gliosis. Dense glial scars have been found to encapsulate implanted devices, corrode their surfaces, and often yield poor recording quality in long-term experiments...
March 21, 2018: Accounts of Chemical Research
Cristina Rodríguez-Seco, Lydia Cabau, Anton Vidal-Ferran, Emilio Palomares
Over hundreds of new organic semiconductor molecules have been synthesized as hole transport materials (HTMs) for perovskite solar cells. However, to date, the well-known N2 , N2 , N2' , N2' , N7 , N7 , N7' , octakis-(4-methoxyphenyl)-9,9-spirobi-[9,9'-spirobi[9 H-fluorene]-2,2',7,7'-tetramine (spiro-OMeTAD) is still the best choice for the best perovskite device performance. Nevertheless, there is a consensus that spiro-OMeTAD by itself is not stable enough for long-term stable devices, and its market price makes its use in large-scale production costly...
March 15, 2018: Accounts of Chemical Research
Bo You, Yujie Sun
Electrocatalytic water splitting driven by renewable energy input to produce clean H2 has been widely viewed as a promising strategy of the future energy portfolio. Currently, the state-of-the-art electrocatalysts for water splitting in acidic solutions are IrO2 or RuO2 for the O2 evolution reaction (OER) and Pt for the H2 evolution reaction (HER). Realization of large-scale H2 production from water splitting requires competent nonprecious electrocatalysts. Despite the advances of decades in this field, several challenges still exist and need to be overcome: (1) Most efforts in the design of nonprecious electrocatalysts have focused on developing HER catalysts for acidic conditions but OER catalysts for alkaline conditions owing to their thermodynamic convenience, potentially resulting in incompatible integration of the two types of catalysts and thus inferior overall performance...
March 14, 2018: Accounts of Chemical Research
David Portehault, Simon Delacroix, Guillaume Gouget, Rémi Grosjean, Tsou-Hsi-Camille Chan-Chang
The design of inorganic nanoparticles relies strongly on the knowledge from solid-state chemistry not only for characterization techniques, but also and primarily for choosing the systems that will yield the desired properties. The range of inorganic solids reported and studied as nanoparticles is however strikingly narrow when compared to the solid-state chemistry portfolio of bulk materials. Efforts to enlarge the collection of inorganic particles are becoming increasingly important for three reasons. First, they can yield materials more performing than current ones for a range of fields including biomedicine, optics, catalysis, and energy...
March 13, 2018: Accounts of Chemical Research
Trisha L Andrew, Lushuai Zhang, Nongyi Cheng, Morgan Baima, Jae Joon Kim, Linden Allison, Steven Hoxie
Body-mountable electronics and electronically active garments are the future of portable, interactive devices. However, wearable devices and electronic garments are demanding technology platforms because of the large, varied mechanical stresses to which they are routinely subjected, which can easily abrade or damage microelectronic components and electronic interconnects. Furthermore, aesthetics and tactile perception (or feel) can make or break a nascent wearable technology, irrespective of device metrics...
March 9, 2018: Accounts of Chemical Research
Melisa Del Barrio, Matteo Sensi, Christophe Orain, Carole Baffert, Sébastien Dementin, Vincent Fourmond, Christophe Léger
Many enzymes that produce or transform small molecules such as O2 , H2 , and CO2 embed inorganic cofactors based on transition metals. Their active site, where the chemical reaction occurs, is buried in and protected by the protein matrix, and connected to the solvent in several ways: chains of redox cofactors mediate long-range electron transfer; static or dynamic tunnels guide the substrate, product and inhibitors; amino acids and water molecules transfer protons. The catalytic mechanism of these enzymes is therefore delocalized over the protein and involves many different steps, some of which determine the response of the enzyme under conditions of stress (extreme redox conditions, presence of inhibitors, light), the catalytic rates in the two directions of the reaction and their ratio (the "catalytic bias")...
March 8, 2018: Accounts of Chemical Research
Sean T Hunt, Yuriy Román-Leshkov
Conspecuts Commercial and emerging renewable energy technologies are underpinned by precious metal catalysts, which enable the transformation of reactants into useful products. However, the noble metals (NMs) comprise the least abundant elements in the lithosphere, making them prohibitively scarce and expensive for future global-scale technologies. As such, intense research efforts have been devoted to eliminating or substantially reducing the loadings of NMs in various catalytic applications. These efforts have resulted in a plethora of heterogeneous NM catalyst morphologies beyond the traditional supported spherical nanoparticle...
March 6, 2018: Accounts of Chemical Research
Yasumasa Takagi, Tomoya Uruga, Mizuki Tada, Yasuhiro Iwasawa, Toshihiko Yokoyama
Heterogeneous interfaces play important roles in a variety of functional material systems and technologies, such as catalysis, batteries, and devices. A fundamental understanding of efficient functions at interfaces under realistic conditions is crucial for sophisticated designs of useful material systems and novel devices. X-ray photoelectron spectroscopy is one of the most promising and common methods to investigate such material systems. Although X-ray photoelectron spectroscopy is usually conducted under high vacuum because of the requirement of electron detection with the precise measurement of kinetic energies, extensive efforts have been devoted to the measurements in gaseous environments...
March 6, 2018: Accounts of Chemical Research
Adam G Kreutzer, James S Nowick
In the more than a century since its identification, Alzheimer's disease has become the archetype of amyloid diseases. The first glimpses of the chemical basis of Alzheimer's disease began with the identification of "amyloid" plaques in the brain in 1892 and extended to the identification of proteinaceous fibrils with "cross-β" structure in 1968. Further efforts led to the discovery of the β-amyloid peptide, Aβ, as a 40- or 42-amino acid peptide that is responsible for the plaques and fibrils...
March 6, 2018: Accounts of Chemical Research
Juwon Oh, Young Mo Sung, Yongseok Hong, Dongho Kim
Aromaticity, the special energetic stability derived from cyclic [4 n + 2]π-conjugated electronic structures, has been the topic of intense interest in chemistry because it plays a critical role in rationalizing molecular stability, reactivity, and physical/chemical properties. Recently, the pioneering work by Colin Baird on aromaticity reversal, postulating that aromatic (antiaromatic) character in the ground state reverses to antiaromatic (aromatic) character in the lowest excited triplet state, has attracted much scientific attention...
March 6, 2018: Accounts of Chemical Research
Christianna N Lininger, Nicholas W Brady, Alan C West
Batteries are dynamic devices composed of multiple components that operate far from equilibrium and may operate under extreme stress and varying loads. Studies of isolated battery components are valuable to the fundamental understanding of the physical processes occurring within each constituent element. When the components are integrated into a full device and operated under realistic conditions, it can be difficult to decouple the physical processes that occur across multiple interfaces and multiple length scales...
March 2, 2018: Accounts of Chemical Research
Xiaoguang Duan, Hongqi Sun, Shaobin Wang
Catalytic processes have remarkably boosted the rapid industrializations in chemical production, energy conversion, and environmental remediation. As one of the emerging applications of carbocatalysis, metal-free nanocarbons have demonstrated promise as catalysts for green remediation technologies to overcome the poor stability and undesirable metal leaching in metal-based advanced oxidation processes (AOPs). Since our reports of heterogeneous activation of persulfates with low-dimensional nanocarbons, the novel oxidative system has raised tremendous interest for degradation of organic contaminants in wastewater without secondary contamination...
March 1, 2018: Accounts of Chemical Research
Zongyang Qiu, Pai Li, Zhenyu Li, Jinlong Yang
Epitaxial growth is a promising strategy to produce high-quality graphene samples. At the same time, this method has great flexibility for industrial scale-up. To optimize growth protocols, it is essential to understand the underlying growth mechanisms. This is, however, very challenging, as the growth process is complicated and involves many elementary steps. Experimentally, atomic-scale in situ characterization methods are generally not feasible at the high temperature of graphene growth. Therefore, kinetics is the main experimental information to study growth mechanisms...
March 1, 2018: Accounts of Chemical Research
Jan K Szymański, Yousef M Abul-Haija, Leroy Cronin
Millions of years of biological evolution have driven the development of highly sophisticated molecular machinery found within living systems. These systems produce polymers such as proteins and nucleic acids with incredible fidelity and function. In nature, the precise molecular sequence is the factor that determines the function of these macromolecules. Given that the ability to precisely define sequence emerges naturally, the fact that biology achieves unprecedented control over the unit sequence of the monomers through evolved enzymatic catalysis is incredible...
March 1, 2018: Accounts of Chemical Research
Seán T Barry, Andrew V Teplyakov, Francisco Zaera
The deposition of thin solid films is central to many industrial applications, and chemical vapor deposition (CVD) methods are particularly useful for this task. For one, the isotropic nature of the adsorption of chemical species affords even coverages on surfaces with rough topographies, an increasingly common requirement in microelectronics. Furthermore, by splitting the overall film-depositing reactions into two or more complementary and self-limiting steps, as it is done in atomic layer depositions (ALD), film thicknesses can be controlled down to the sub-monolayer level...
February 28, 2018: Accounts of Chemical Research
Dalong Ni, Dawei Jiang, Emily B Ehlerding, Peng Huang, Weibo Cai
As one of the most biocompatible and well-tolerated inorganic nanomaterials, silica-based nanoparticles (SiNPs) have received extensive attention over the last several decades. Recently, positron emission tomography (PET) imaging of radiolabeled SiNPs has provided a highly sensitive, noninvasive, and quantitative readout of the organ/tissue distribution, pharmacokinetics, and tumor targeting efficiency in vivo, which can greatly expedite the clinical translation of these promising NPs. Encouraged by the successful PET imaging of patients with metastatic melanoma using124 I-labeled ultrasmall SiNPs (known as Cornell dots or C dots) and their approval as an Investigational New Drug (IND) by the United States Food and Drug Administration, different radioisotopes (64 Cu,89 Zr,18 F,68 Ga,124 I, etc...
February 28, 2018: Accounts of Chemical Research
Zhaowei Chen, Zhenzhen Wang, Jinsong Ren, Xiaogang Qu
Bacterial infection continues to be a growing global health problem with the most widely accepted treatment paradigms restricted to antibiotics. However, antibiotics overuse and misuse have triggered increased multidrug resistance, frustrating the therapeutic outcomes and leading to higher mortalities. Even worse, the tendency of bacteria to form biofilms on living and nonliving surfaces further increases the difficulty in confronting bacteria because the extracellular matrix can act as a robust barrier to prevent the penetration of antibiotics and resist environmental stress...
February 28, 2018: Accounts of Chemical Research
Limin Zhang, Yang Tian
The in vivo analysis of chemical signals in brain extracellular fluid (ECF) using implanted electrochemical biosensors is a vital way to study brain functions and brain activity mapping. This approach offers excellent spatial (10-200 μm) and temporal (approximately second) resolution and the major advantage of long-term stability. By implantation of a microelectrode in a specific brain region, changes in the concentration of a variety of ECF chemical species can be monitored through applying a suitable electrical signal and, typically, recording the resulting Faradaic current...
February 27, 2018: Accounts of Chemical Research
Lipiao Bao, Ping Peng, Xing Lu
Concrete crystallographic results of endohedral metallofullerenes (EMFs) disclose that the bonding within the metallic clusters and the interactions between the metal ions and the cage carbon atoms, which are closely associated with the coordination ability of the metal ions, play essential roles in determining the stability, the molecular structure, and the chemical behavior of the hybrid EMF molecules, in addition to the previously recognized charge transfer from metal to cage. For the carbide cluster metallofullerenes, a "size effect" between the encapsulated metallic cluster and the fullerene cage has been suggested...
February 27, 2018: Accounts of Chemical Research
Wei-Lin Leng, Hui Yao, Jing-Xi He, Xue-Wei Liu
Glycans are complex compounds consisting of sugars linked glycosidically, existing either as pure polysaccharides or as part of glycoconjugates. They are prevalent in nature and possess important functions in regulating biological pathways. However, their diversity coupled with physiochemical similarities makes it challenging to isolate them in large quantities for biochemical studies, hence hampering progress in glycobiology and glycomedicine. Glycochemistry presents an alternative strategy to obtain pure glycan compounds through artificial synthetic methods...
February 22, 2018: Accounts of Chemical Research
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