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https://www.readbyqxmd.com/read/28632333/from-chemical-topology-to-molecular-machines-nobel-lecture
#1
REVIEW
Jean-Pierre Sauvage
To a large extent, the field of "molecular machines" started after several groups were able to prepare, reasonably easily, interlocking ring compounds (named catenanes for compounds consisting of interlocking rings and rotaxanes for rings threaded by molecular filaments or axes). Important families of molecular machines not belonging to the interlocking world were also designed, prepared, and studied but, for most of them, their elaboration was more recent than that of catenanes or rotaxanes. Since the creation of interlocking ring molecules is so important in relation to the molecular machinery area, we will start with this aspect of our work...
June 20, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28626559/reversible-mechanical-protection-building-a-3d-suit-around-a-t-shaped-benzimidazole-axle
#2
Kelong Zhu, Giorgio Baggi, V Nicholas Vukotic, Stephen J Loeb
The T-shaped benzimidazolium/crown ether recognition motif was used to prepare suit[1]anes. These novel mechanically interlocked molecules (MIMs) were fully characterized by (1)H and (13)C NMR spectroscopy, single-crystal X-ray diffraction, UV-vis absorption and fluorescence spectroscopy. By conversion to a suit[1]ane, a simple benzimidazole was shown to be protected from deprotonation by strong base. Moreover, it was demonstrated that this unique three-dimensional encapsulation can be made reversible, thus introducing the concept of "reversible mechanical protection"; a protecting methodology that may have potential applications in synthetic organic chemistry and the design of molecular machinery...
May 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28625476/feedback-loops-interlocked-at-competitive-binding-sites-amplify-and-facilitate-genetic-oscillations
#3
Koichiro Uriu, Hajime Tei
Positive and negative feedback loops are often present in regulatory networks for genetic oscillations. Relative time scales and integration of these feedback loops are key to robust oscillations in expression levels. Using examples from the circadian clock and synthetic genetic oscillators, we study positive and negative feedback loops interlocked at competitive binding sites. In the mammalian circadian clock, a key clock gene Bmal1 is regulated by the activator ROR and the repressor REV-ERB. Conversely, Bmal1 activates both of them, forming interlocked feedback loops...
June 15, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28623269/theory-of-inverse-edelstein-effect-of-the-surface-states-of-a-topological-insulator
#4
H Geng, W Luo, W Y Deng, L Sheng, R Shen, D Y Xing
The surface states of three-dimensional topological insulators possess the unique property of spin-momentum interlocking. This property gives rise to the interesting inverse Edelstein effect (IEE), in which an applied spin bias μ is converted to a measurable charge voltage difference V. We develop a semiclassical theory for the IEE of the surface states of Bi2Se3 thin films, which is applicable from the ballistic regime to diffusive regime. We find that the efficiency of the spin-charge conversion, defined as γ = V/μ, exhibits a universal dependence on the ratio between sample size and electron mean free path...
June 16, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28617467/a-wet-tolerant-adhesive-patch-inspired-by-protuberances-in-suction-cups-of-octopi
#5
Sangyul Baik, Da Wan Kim, Youngjin Park, Tae-Jin Lee, Suk Ho Bhang, Changhyun Pang
Adhesion strategies that rely on mechanical interlocking or molecular attractions between surfaces can suffer when coming into contact with liquids. Thus far, artificial wet and dry adhesives have included hierarchical mushroom-shaped or porous structures that allow suction or capillarity, supramolecular structures comprising nanoparticles, and chemistry-based attractants that use various protein polyelectrolytes. However, it is challenging to develop adhesives that are simple to make and also perform well-and repeatedly-under both wet and dry conditions, while avoiding non-chemical contamination on the adhered surfaces...
June 14, 2017: Nature
https://www.readbyqxmd.com/read/28611571/exosomes-and-homeostatic-synaptic-plasticity-are-linked-to-each-other-and-to-huntington-s-parkinson-s-and-other-neurodegenerative-diseases-by-database-enabled-analyses-of-comprehensively-curated-datasets
#6
James K T Wang, Peter Langfelder, Steve Horvath, Michael J Palazzolo
Huntington's disease (HD) is a progressive and autosomal dominant neurodegeneration caused by CAG expansion in the huntingtin gene (HTT), but the pathophysiological mechanism of mutant HTT (mHTT) remains unclear. To study HD using systems biological methodologies on all published data, we undertook the first comprehensive curation of two key PubMed HD datasets: perturbation genes that impact mHTT-driven endpoints and therefore are putatively linked causally to pathogenic mechanisms, and the protein interactome of HTT that reflects its biology...
2017: Frontiers in Neuroscience
https://www.readbyqxmd.com/read/28597401/biomechanical-evaluation-of-the-risk-of-secondary-fracture-around-short-versus-long-cephalomedullary-nails
#7
William E Daner Iii, John R Owen, Jennifer S Wayne, Ryan B Graves, Mark C Willis
INTRODUCTION: For proximal femur fractures, long cephalomedullary nails (CMNs) are often selected to avoid a diaphyseal stress riser at the tip of a shorter nail. Secondary peri-implant fracture rates for long and short CMN have not been shown to differ clinically. This study biomechanically compares both CMN in a cadaveric model. METHODS: Ten matched pairs of cadaveric femora with short or long CMN were axially loaded and internally rotated to failure. RESULTS: Resulting fractures involved distal interlocking screws of the short and long CMN...
June 8, 2017: European Journal of Orthopaedic Surgery & Traumatology: Orthopédie Traumatologie
https://www.readbyqxmd.com/read/28596811/genetic-engineering-and-human-mental-ecology-interlocking-effects-and-educational-considerations
#8
Ramsey Affifi
This paper describes some likely semiotic consequences of genetic engineering on what Gregory Bateson has called "the mental ecology" (1979) of future humans, consequences that are less often raised in discussions surrounding the safety of GMOs (genetically modified organisms). The effects are as follows: an increased 1) habituation to the presence of GMOs in the environment, 2) normalization of empirically false assumptions grounding genetic reductionism, 3) acceptance that humans are capable and entitled to decide what constitutes an evolutionary improvement for a species, 4) perception that the main source of creativity and problem solving in the biosphere is anthropogenic...
2017: Biosemiotics
https://www.readbyqxmd.com/read/28590726/anion-and-solvent-induced-rotary-dynamics-and-sensing-in-a-perylene-diimide-3-catenane
#9
Timothy Andrew Barendt, Liliana Ferreira, Igor Marques, Vitor Felix, Paul D Beer
A novel dynamic [3]catenane consisting of a large four-station central macrocycle which incorporates a bay tetrachloro-functionalized perylene diimide (PDI) unit and two triazolium anion binding motifs, mechanically bonded with two smaller isophthalamide-containing macrocycles is constructed using an anion template synthetic methodology. Proton NMR, electronic absorption and fluorescence emission spectroscopies together with molecular dynamics simulations are used to investigate the anion recognition- and solvent-dependent dynamic properties of the higher-order mechanically interlocked molecule...
June 7, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28590129/high-level-production-and-properties-of-the-cysteine-depleted-cytochrome-p450-3a4
#10
Irina F Sevrioukova
Human drug-metabolizing cytochrome P450 3A4 (CYP3A4) is a dynamic enzyme with a large and highly malleable active site that can fit structurally diverse compounds. Despite extensive investigations, structure-function relationships and conformational dynamics in CYP3A4 are not fully understood. This study was undertaken to engineer a well-expressed and functionally active cysteine-depleted CYP3A4 that can be used in biochemical and biophysical studies. cDNA codon optimization and screening mutagenesis were utilized to boost the level of bacterial expression of CYP3A4 and identify the least harmful substitutions for all six non-heme-ligating cysteines...
June 7, 2017: Biochemistry
https://www.readbyqxmd.com/read/28586586/comparative-analysis-of-anterior-knee-pain-in-transpatellar-and-medial-parapatellar-tendon-approaches-in-tibial-interlocking-nailing
#11
Saeed Ahmad, Ashfaq Ahmed, Latif Khan, Shahzad Javed, Naeem Ahmed, Amer Aziz
OBJECTIVE: Anterior knee pain is the most common complaint after intramedullary nail of the tibia. The incidence of anterior knee pain ranges from 10-86% and the exact ethology is unclear. Transpatellar tendon approach is commonly used for tibial intramedullary interlocking nailing but it can also be done through medial parapatellar tendon approach. The objective of the study was to compare post-operative anterior knee pain after intramedullary nailing technique by transpatellar approach compared to medial parapatellar approach...
October 2016: Journal of Ayub Medical College, Abbottabad: JAMC
https://www.readbyqxmd.com/read/28584887/intramedullary-tibial-nailing-of-distal-tibiofibular-fractures-additional-fibular-fixation-or-not
#12
M Van Maele, B Molenaers, E Geusens, S Nijs, H Hoekstra
INTRODUCTION: The anatomy of the distal tibia accounts for reduced biomechanical stability and higher complication rates when treating distal tibiofibular fractures with an intramedullary tibia nail (IMTN). The goal of this study was to identify variables that affect the stability of IMTN. We assessed the value of additional fibular fixation, angular stable interlocking screws (ASLS) and multiplanar screw configuration in IMTN. PATIENTS AND METHODS: A retrospective cohort study was performed including 184 distal tibial fractures and associated fibula fracture treated with IMTN...
June 5, 2017: European Journal of Trauma and Emergency Surgery: Official Publication of the European Trauma Society
https://www.readbyqxmd.com/read/28584799/transcatheter-occlusion-of-a-giant-pulmonary-arteriovenous-malformation-in-a-1-year-old-child-using-amplatzer-vascular-plugs-and-interlocking-detachable-coils
#13
https://www.readbyqxmd.com/read/28582266/a-beam-monitoring-and-validation-system-for-continuous-line-scanning-in-proton-therapy
#14
Grischa Klimpki, Serena Psoroulas, Christian Bula, Urs Rechsteiner, Michael Eichin, Damien Weber, Antony Lomax, David Meer
Line scanning represents a faster and potentially more flexible form of pencil beam scanning than conventional <i>step-and-shoot</i> irradiations. It seeks to minimize dead times in beam delivery whilst preserving the possibility to modulate the dose at any point in the target volume. Our second generation proton gantry features irradiations in line scanning mode, but it still lacks a dedicated monitoring and validation system that guarantees patient safety throughout beam delivery. We report on its design and implementation in this paper...
June 5, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28580109/photoswitchable-interlocked-thiodiglycolamide-as-a-cocatalyst-of-a-chalcogeno-baylis-hillman-reaction
#15
Alberto Martinez-Cuezva, Adrian Saura-Sanmartin, Tomas Nicolas-Garcia, Cristian Navarro, Raul-Angel Orenes, Mateo Alajarin, Jose Berna
En route to a photoswitchable interlocked catalyst we have proved the ability of thiodiglycolamide to act as a template in the formation of hydrogen-bonded [2]rotaxanes. X-ray diffraction studies reveal the shielding of the sulfide atom by the macrocycle. A series of molecular shuttles are described as having an isomerizable fumaramide and thiodiglycolamide binding sites for controlling the relative ring position at will. By employing these systems as photoregulated catalysts, the TiCl4-mediated chalcogeno-Morita-Baylis-Hillman reaction is tested...
May 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28578578/synthesis-of-gold-nanoparticles-from-au-i-ions-shuttle-to-solidify-application-on-the-sensor-array-design
#16
Yumin Leng, Kai Jiang, Wentai Zhang, Yuhui Wang
Metal-mediated interlocking rings won the 2016 Nobel Prize in Chemistry. The metal-directed interlocking rings in macromolecular systems (e.g. proteins) may be similar to the form of Maxwell's electromagnetic waves, the metal ions may shuttle among the rings in the special environment. To verify this hypothesis, we designed a general approach to synthesize the multicolor gold nanoparticles (GNPs) mediated by Au(I)-directed interlocking rings in proteins. The Au(I) ions shuttled among these interlocking rings in the strong alkaline solution...
June 5, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28574220/functional-mechanically-interlocked-molecules-asymmetric-organocatalysis-with-a-catenated-bifunctional-br%C3%A3-nsted-acid
#17
Raja Mitra, Hui Zhu, Stefan Grimme, Jochen Niemeyer
Interlocked molecules, such as catenanes, rotaxanes and molecular knots, have become interesting candidates for the development of sophisticated chemical catalysts. Herein, we report the first application of a catenane-based catalyst in asymmetric organocatalysis, revealing that the catenated catalyst shows dramatically increased stereoselectivities (up to 98% ee) in comparison to its non-interlocked analogues. A mechanistic rationale for the observed differences was developed by DFT-studies, suggesting that the involvement of two catalytically active groups in the stereodetermining reaction step is responsible for the superior selectivity of the interlocked catalyst...
June 2, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28573210/topology-engineering-of-proteins-in-vivo-using-genetically-encoded-mechanically-interlocking-spyx-modules-for-enhanced-stability
#18
Dong Liu, Wen-Hao Wu, Ya-Jie Liu, Xia-Ling Wu, Yang Cao, Bo Song, Xiaopeng Li, Wen-Bin Zhang
Recombinant proteins are traditionally limited to linear configuration. Herein, we report in vivo protein topology engineering using highly efficient, mechanically interlocking SpyX modules named AXB and BXA. SpyX modules are protein domains composed of p53dim (X), SpyTag (A), and SpyCatcher (B). The p53dim guides the intertwining of the two nascent protein chains followed by autocatalytic isopeptide bond formation between SpyTag and SpyCatcher to fulfill the interlocking, leading to a variety of backbone topologies...
May 24, 2017: ACS Central Science
https://www.readbyqxmd.com/read/28572554/-die-symmetrie-von-spiralketten
#19
Ulrich Müller
In crystals, polymeric chain molecules often adopt helical structures. Neglecting small distortions possibly caused by an anisotropic environment within the crystal, the symmetry of the single helix can be described by a rod group, which has translational symmetry in one dimension. The rod groups have Hermann-Mauguin symbols similar to space groups, beginning with a script style \scr p followed by a screw-axis symbol; the order of the screw axis can adopt any value. In a crystal, the rod-site symmetry, the so-called penetration rod group, must be a common crystallographic rod subgroup of the molecular rod group and the space group...
June 1, 2017: Acta Crystallographica Section B, Structural Science, Crystal Engineering and Materials
https://www.readbyqxmd.com/read/28571220/interlocking-nailing-versus-plating-in-tibial-shaft-fractures-in-adults-a-comparative-study
#20
Sagnik Mukherjee, Mahendra Singh Arambam, Sanjib Waikhom, Santosha, Pranav Vitthal Masatwar, Rohan Gautam Maske
INTRODUCTION: Tibial diaphyseal fractures are the commonest long bone fractures in adults, most commonly managed by intramedullary interlocking nailing. However, several meta-analysis show that locking plate osteosynthesis is equally effective in managing tibial diaphyseal fractures and are associated with less number of complications. AIM: To compare the results of fixation of tibial fractures following plating and nailing in terms of union, patient satisfaction and complications...
April 2017: Journal of Clinical and Diagnostic Research: JCDR
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