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Subtle energies

Consuelo Badilla, Thomas H Osborne, Ambrose Cole, Cameron Watson, Snezana Djordjevic, Joanne M Santini
Arsenic contamination of drinking water affects more than 140 million people worldwide. While toxic to humans, inorganic forms of arsenic (arsenite and arsenate), can be used as energy sources for microbial respiration. AioX and its orthologues (ArxX and ArrX) represent the first members of a new sub-family of periplasmic-binding proteins that serve as the first component of a signal transduction system, that's role is to positively regulate expression of arsenic metabolism enzymes. As determined by X-ray crystallography for AioX, arsenite binding only requires subtle conformational changes in protein structure, providing insights into protein-ligand interactions...
April 19, 2018: Scientific Reports
Jishan Wu, Guangwu Li, Tullimilli Y Gopalakrishna, Hoa Phan, Tun Seng Tun Seng Herng, Jun Ding
A dithieno[a,h]-s-indacene (DTI) based diradicaloid DTI-2Br was synthesized and its open-shell singlet diradical character was validated by magnetic measurements. On the other hand, its macrocyclic trimer DTI-MC3 and tetramer DTI-MC4 turned out to be closed-shell compounds with global anti-aromaticity, which was supported by X-ray crystallographic analysis and NMR spectra, assisted by ACID and 2D-NICS calculations. Such change can be explained by a subtle balance between two types of anti-ferromagnetic spin-spin coupling along the π-conjugated macrocycles...
April 19, 2018: Angewandte Chemie
Lei Xu, Dayu Li, Junjie Ding, Li Pan, Xiaoqin Ding
Nav 1.2, a member of voltage-gated sodium channels (Nav s) that are responsible for the generation and propagation of action potentials along the cell membrane, and play a vital role in the process of information transmission within the nervous system and muscle contraction, is preferentially expressed in the central nervous system. As a potent and selective blocker of Nav s, tetrodotoxin (TTX) has been extensively studied in biological and chemical sciences, whereas the detailed mechanism by which it blocks nine Nav 1 channel subtypes remain elusive...
April 19, 2018: Chemical Biology & Drug Design
Tardu Özkartal, François Regoli, Giulio Conte, Maria Luce Caputo, Catherine Klersy, Tiziano Moccetti, Angelo Auricchio
Aims: Phrenic nerve palsy (PNP) after mechanical transvenous lead extraction (TLE) was recently described for the first time. We aimed to analyse our TLE database for the presence of PNP. Methods and results: All consecutive patients referred to our institution were included in this study. Every available post-procedural chest X-ray was compared to the routinely performed pre-procedural radiographs. A newly elevated hemidiaphragm ipsilateral to TLE was considered indicative of PNP...
April 16, 2018: Europace: European Pacing, Arrhythmias, and Cardiac Electrophysiology
Shahrukh Husain, Vijay Kumar, Md Imtaiyaz Hassan
Tank binding kinase 1 (TBK-1) plays an important role in immunity, inflammation, autophagy, cell growth and proliferation. Nevertheless, a key molecular and structural detail of TBK-1 phosphorylation and activation has been largely unknown. Here we investigated the energy landscape of phosphorylated (active) and unphosphorylated (inactive) forms of human TBK-1 to characterize the interplay between phosphorylation and local frustration. By employing the algorithm equipped with energy function and implemented in Frustratometer web-server (http://www...
April 10, 2018: Journal of Theoretical Biology
Chenyi Fei, Yuansheng Cao, Qi Ouyang, Yuhai Tu
Biological systems need to function accurately in the presence of strong noise and at the same time respond sensitively to subtle external cues. Here we study design principles in biochemical oscillatory circuits to achieve these two seemingly incompatible goals. We show that energy dissipation can enhance phase sensitivity linearly by driving the phase-amplitude coupling and increase timing accuracy by suppressing phase diffusion. Two general design principles in the key underlying reaction loop formed by two antiparallel pathways are found to optimize oscillation performance with a given energy budget: balancing the forward-to-backward flux ratio between the two pathways to reduce phase diffusion and maximizing the net flux of the phase-advancing pathway relative to that of the phase-retreating pathway to enhance phase sensitivity...
April 12, 2018: Nature Communications
Tomohisa Nagasao, Tadaaki Morotomi, Motone Kuriyama, Motoki Tamai, Yoshiaki Sakamoto, Naoki Takano
PURPOSE: Detection of optic canal fractures is often difficult because of the subtleness of the fracture. If we could clarify impact on which region around the orbit is likely to accompany the fracture of the optic canal, the knowledge should be useful to make early diagnosis of optic canal fractures. The present study was conducted to elucidate this issue. METHODS: Ten finite element models were produced simulating the skulls of ten humans (8 males and 2 females; 43...
December 2018: Computer Assisted Surgery (Abingdon, England)
Yue Zhang, Weikang Gong, Yan Wang, Yang Liu, Chunhua Li
Human P-glycoprotein (P-gp), a kind of ATP-Binding Cassette transporter, can export a diverse variety of anti-cancer drugs out of the tumor cell. Its overexpression is one of the main reasons for the multidrug resistance (MDR) of tumor cells. It has been confirmed that during the substrate transport process, P-gp experiences a large-scale structural rearrangement from the inward- to outward-facing states. However, the mechanism of how the nucleotide-binding domains (NBDs) control the transmembrane domains (TMDs) to open towards the periplasm in the outward-facing state has not yet been fully characterized...
April 5, 2018: Journal of Biomolecular Structure & Dynamics
Leszek M Malec, Marlena Gryl, Katarzyna M Stadnicka
New nontoxic and biocompatible ferroelectric materials are a subject undergoing intense study. One of the most promising research branches is focused on H-bonded organic or hybrid ferroelectrics. The engineering of these materials is based on mimicking the phase transition mechanisms of the well-known inorganic ferroelectrics. In our study, a coupled experimental and theoretical methodology was used for a precise investigation of the ferroelectric phase transition mechanism in ammonium sulfate (AS). A series of single-crystal X-ray diffraction measurements were performed in the temperature range between 273 and 163 K...
April 4, 2018: Inorganic Chemistry
Monima Sarma, Ken-Tsung Wong
Organic materials that display thermally activated delayed fluorescence (TADF) are a striking class of functional materials that have witnessed a booming progress in recent years. In addition to pure TADF emitters achieved by the subtle manipulations of intramolecular charge transfer processes with sophisticated molecular structures, a new class of efficient TADF-based OLEDs with emitting layer formed by blending electron donor and acceptor molecules that involve intermolecular charge transfer have also been fabricated...
April 3, 2018: ACS Applied Materials & Interfaces
David Garcia-Burgos, Sabine Maglieri, Claus Vögele, Simone Munsch
Background: Despite on-going efforts to better understand dysregulated eating, the olfactory-gustatory deficits and food preferences in eating disorders (ED), and the mechanisms underlying the perception of and responses to food properties in anorexia nervosa (AN) and bulimia nervosa (BN) remain largely unknown; both during the course of the illness and compared to healthy populations. It is, therefore, necessary to systematically investigate the gustatory perception and hedonics of taste in patients with AN and BN...
2018: Frontiers in Psychology
Srikanth Reddy Tulsani, Arup Kumar Rath
The solution-processed quantum dot (QD) solar cell technology has seen significant advancements in recent past to emerge as a potential contender for the next generation photovoltaic technology. In the development of high performance QD solar cell, the surface ligand chemistry has played the important role in controlling the doping type and doping density of QD solids. For instance, lead sulfide (PbS) QDs which is at the forefront of QD solar cell technology, can be made n-type or p-type respectively by using iodine or thiol as the surfactant...
March 15, 2018: Journal of Colloid and Interface Science
Andres Cordoba
Active gels perform key mechanical roles inside the cell, such as cell division, motion and force sensing. The unique mechanical properties required to perform such functions arise from the interactions between molecular motors and semi-flexible polymeric filaments. Molecular motors can convert the energy released in the hydrolysis of ATP into forces of up to pico- Newton magnitudes. Moreover, the polymeric filaments that form active gels are flexible enough to respond to Brownian forces, but also stiff enough to support the large tensions in- duced by the motor-generated forces...
March 26, 2018: Journal of Physical Chemistry. B
Zhenyu Meng, Tomas Kubar, Yuguang Mu, Fangwei Shao
Charge transport (CT) through biomolecules is of high significance in the research fields of biology, nanotechnology, and molecular devices. Inspired by our previous work which showed the binding of ionic liquid (IL) facilitated charge transport in duplex DNA, in silico simulation is a useful means to understand the microscopic mechanism of the facilitation phenomenon. Here molecular dynamics simulations (MD) of duplex DNA in water and hydrated ionic liquids were employed to explore the helical parameters. Principal component analysis was further applied to capture the subtle conformational changes of helical DNA upon different environmental impacts...
March 23, 2018: Journal of Chemical Theory and Computation
Cyprian Lewandowski, L S Levitov
In Dirac materials linear band dispersion blocks momentum-conserving interband transitions, creating a bottleneck for electron-hole pair production and carrier multiplication in the photoexcitation cascade. Here we show that the decays are unblocked and the bottleneck is relieved by subtle many-body effects involving multiple off-shell e-h pairs. The decays result from a collective behavior due to simultaneous emission of many soft pairs. We discuss characteristic signatures of the off-shell pathways, in particular the sharp angular distribution of secondary carriers, resembling relativistic jets in high-energy physics...
February 16, 2018: Physical Review Letters
M R Calvo, C Sabater, W Dednam, E B Lombardi, M J Caturla, C Untiedt
Our analysis of the contact formation processes undergone by Au, Ag, and Cu nanojunctions reveals that the distance at which the two closest atoms on a pair of opposing electrodes jump into contact is, on average, 2 times longer for Au than either Ag or Cu. This suggests the existence of a longer-range interaction between those two atoms in the case of Au, a result of the significant relativistic energy contributions to the electronic structure of this metal, as confirmed by ab initio calculations. Once in the contact regime, the differences between Au, Ag, and Cu are subtle, and the conductance of single-atom contacts for metals of similar chemical valence is mostly determined by geometry and coordination...
February 16, 2018: Physical Review Letters
Adejoke N Kolawole, Valentine T Akinladejo, Olusola O Elekofehinti, Afolabi C Akinmoladun, Ayodele O Kolawole
Aldehyde dehydrogenases (ALDHs) are a diverse family of enzymes that catalyze the NAD(P)+ -dependent detoxification of toxic aldehyde compounds. ALDHs are also involved in non-enzymatic ligand binding to endobiotics and xenobiotics. Here, the enzyme crucial non-canonical and non-catalytic interaction with kolaflavanone, a component of kolaviron, and a major bioflavonoid isolated from Garcinia kola (Bitter kola) was characterized by various spectroscopic and in silico approaches under stimulated physiological condition...
February 27, 2018: Bioorganic Chemistry
Jeremy R Wortman, Jennifer W Uyeda, Urvi P Fulwadhva, Aaron D Sodickson
Computed tomography (CT) is key to the assessment of hemodynamically stable patients with blunt or penetrating trauma to the abdomen and pelvis. Dual-energy (DE) CT is a technology that allows acquisition of data at both high and low kilovolt peaks, allowing materials that have different x-ray absorption behaviors as a function of kilovolt peak (such as iodine) to be differentiated and quantified. DE CT has a variety of postprocessing applications that may be helpful in abdominal and pelvic trauma, including iodine-selective imaging, virtual monenergetic imaging, and virtual noncalcium imaging...
March 2018: Radiographics: a Review Publication of the Radiological Society of North America, Inc
Pi Liu, Yan Zhao, Xiaoguo Liu, Jixue Sun, Dede Xu, Yang Li, Qian Li, Lihua Wang, Sichun Yang, Chunhai Fan, Jianping Lin
Shape reconfiguration of membrane protein channels is highly regulated under physiological conditions for gated transportation. Nevertheless, mechanistic understanding of molecular channels remains challenging due to the difficulty in probing gating-associated subtle structural changes. Here we show that charge neutralization can drive shape reconfiguration of a biomimetic 6-helix bundle DNA nanotube (6HB). Specifically, 6HB adopts a compact state when being neutralized by Mg2+; and monovalent ions (Na+) switch it to the expansion state, as revealed by molecular dynamics (MD) simulation, small angle X-ray scattering (SAXS) and Förster resonance energy transfer (FRET) characterization...
March 12, 2018: Angewandte Chemie
Camilla Calabrese, Assimo Maris, Luca Evangelisti, Anna Piras, Valentina Parravicini, Sonia Melandri
We describe an experimental and quantum chemical study for the accurate determination of the conformational space of small molecular systems governed by intramolecular non-covalent interactions. The model systems investigated belong to the biological relevant aminoalcohol's family, and include 2-amino-1-phenylethanol, 2-methylamino-1-phenylethanol, noradrenaline, adrenaline 2-aminoethanol, and N -methyl-2-aminoethanol. For the latter molecule, the rotational spectrum in the 6-18 and 59.6-74.4 GHz ranges was recorded in the isolated conditions of a free jet expansion...
2018: Frontiers in Chemistry
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