keyword
MENU ▼
Read by QxMD icon Read
search

Directed Evolution

keyword
https://www.readbyqxmd.com/read/28735548/strain-driven-shape-evolution-of-stacked-in-ga-n-quantum-disks-embedded-in-gan-nanowires
#1
Javier Bartolomé, Michael Hanke, David van Treeck, Achim Trampert
The fabrication of nanowires with axial multi-quantum wells or disks presenting a homogeneous size and shape distribution along the whole stack is still an unresolved challenge, despite of being essential for narrowing their light emission bandwidth. In this work we demonstrate that the commonly observed change in the shape of the disks along the stacking direction proceeds in a systematic, predictable way. High- resolution transmission electron microscopy of stacked (In,Ga)N quantum discs embedded in GaN nanowires with diameters of ~40 nm and lengths of ~700 nm, and finite element method calculations show that, contrary to what is normally assumed, this change is not related to the radial growth of the nanowires, which is shown to be negligible, but to the strain relaxation of the whole active region...
July 22, 2017: Nano Letters
https://www.readbyqxmd.com/read/28735145/metabolic-gene-targeted-monitoring-of-non-starter-lactic-acid-bacteria-during-cheese-ripening
#2
Alessia Levante, Francesca De Filippis, Antonietta La Storia, Monica Gatti, Erasmo Neviani, Danilo Ercolini, Camilla Lazzi
Long ripened cheeses, such as Grana Padano (GP), a Protected Designation of Origin (PDO) Italian cheese, harbor a viable microbiota mainly composed of non-starter lactic acid bacteria (NSLAB), which contribute to the final characteristics of cheese. The NSLAB species Lactobacillus rhamnosus, Lb. casei and Lb. paracasei are frequently found in GP, and form a closely related taxonomic group (Lb. casei group), making it difficult to distinguish the three species through 16S rRNA sequencing. SpxB, a metabolic gene coding for pyruvate oxidase in Lb...
July 6, 2017: International Journal of Food Microbiology
https://www.readbyqxmd.com/read/28734362/discrimination-of-bacteria-by-rapid-sensing-their-metabolic-volatiles-using-an-aspiration-type-ion-mobility-spectrometer-a-ims-and-gas-chromatography-mass-spectrometry-gc-ms
#3
Ileana Andreea Ratiu, Victor Bocos-Bintintan, Adrian Patrut, Victor Hugo Moll, Matthew Turner, C L Paul Thomas
The objective of our study was to investigate whether one may quickly and reliably discriminate different microorganism strains by direct monitoring of the headspace atmosphere above their cultures. Headspace samples above a series of in vitro bacterial cultures were directly interrogated using an aspiration type ion mobility spectrometer (a-IMS), which produced distinct profiles ("fingerprints") of ion currents generated simultaneously by the detectors present inside the ion mobility cell. Data processing and analysis using principal component analysis showed net differences in the responses produced by volatiles emitted by various bacterial strains...
August 22, 2017: Analytica Chimica Acta
https://www.readbyqxmd.com/read/28734049/development-of-aptamers-against-unpurified-proteins
#4
Shinichi Goto, Kaori Tsukakoshi, Kazunori Ikebukuro
SELEX (Systematic Evolution of Ligands by EXponential enrichment) has been widely used for the generation of aptamers against target proteins. However, its requirement for pure target proteins remains a major problem in aptamer selection, as procedures for protein purification from crude bio-samples are not only complicated but also time and labour consuming. This is because native proteins can be found in a large number of diverse forms because of posttranslational modifications and their complicated molecular conformations...
July 22, 2017: Biotechnology and Bioengineering
https://www.readbyqxmd.com/read/28733625/electronic-structure-of-polyethylene-role-of-chemical-morphological-and-interfacial-complexity
#5
Lihua Chen, Tran Doan Huan, Rampi Ramprasad
The electronic structure of an insulator encodes essential signatures of its short-term electrical performance and long-term reliability. A critical long-standing challenge though is that key features of the electronic structure of an insulator (and its evolution) under realistic conditions have not been entirely accessible, either via experimental or computational approaches, due to the inherent complexities involved. In this comprehensive study, we reveal the role of chemical and morphological imperfections that inevitably exist within the technologically important prototypical and pervasive insulator, polyethylene (PE), and at electrode/PE interfaces...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28733585/robust-hierarchical-3d-carbon-foam-electrode-for-efficient-water-electrolysis
#6
Tung Ngoc Pham, Tiva Sharifi, Robin Sandström, William Siljebo, Andrey Shchukarev, Krisztian Kordas, Thomas Wågberg, Jyri-Pekka Mikkola
Herein we report a 3D heterostructure comprising a hierarchical macroporous carbon foam that incorporates mesoporous carbon nanotubes decorated with cobalt oxide nanoparticles as an unique and highly efficient electrode material for the oxygen evolution reaction (OER) in electrocatalytic water splitting. The best performing electrode material showed high stability after 10 h, at constant potential of 1.7 V vs. RHE (reversible hydrogen electrode) in a 0.1 M KOH solution and high electrocatalytic activity in OER with low overpotential (0...
July 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28731829/pattern-and-process-in-the-comparative-study-of-convergent-evolution
#7
D Luke Mahler, Marjorie G Weber, Catherine E Wagner, Travis Ingram
Understanding processes that have shaped broad-scale biodiversity patterns is a fundamental goal in evolutionary biology. The development of phylogenetic comparative methods has yielded a tool kit for analyzing contemporary patterns by explicitly modeling processes of change in the past, providing neontologists tools for asking questions previously accessible only for select taxa via the fossil record or laboratory experimentation. The comparative approach, however, differs operationally from alternative approaches to studying convergence in that, for studies of only extant species, convergence must be inferred using evolutionary process models rather than being directly measured...
August 2017: American Naturalist
https://www.readbyqxmd.com/read/28731825/convergent-phenotypic-evolution-despite-contrasting-demographic-histories-in-the-fauna-of-white-sands
#8
Erica Bree Rosenblum, Christine E Parent, Eveline T Diepeveen, Clay Noss, Ke Bi
When are evolutionary outcomes predictable? Cases of convergent evolution can shed light on when, why, and how different species exhibit shared evolutionary trajectories. In particular, studying diverse species in a common environment can illuminate how different factors facilitate or constrain adaptive evolution. Here we integrate studies of pattern and process in the fauna at White Sands (New Mexico) to understand the determinants of convergent evolution. Numerous animal species at White Sands exhibit phenotypic convergence in response to a novel-and shared-selective environment: geologically young gypsum dunes...
August 2017: American Naturalist
https://www.readbyqxmd.com/read/28731798/most-colorful-example-of-genetic-assimilation-exploring-the-evolutionary-destiny-of-recurrent-phenotypic-accommodation
#9
Alexander V Badyaev, Ahva L Potticary, Erin S Morrison
Evolution of adaptation requires both generation of novel phenotypic variation and retention of a locally beneficial subset of this variation. Such retention can be facilitated by genetic assimilation, the accumulation of genetic and molecular mechanisms that stabilize induced phenotypes and assume progressively greater control over their reliable production. A particularly strong inference into genetic assimilation as an evolutionary process requires a system where it is possible to directly evaluate the extent to which an induced phenotype is progressively incorporated into preexisting developmental pathways...
August 2017: American Naturalist
https://www.readbyqxmd.com/read/28731794/a-neutral-model-for-the-evolution-of-diet-breadth
#10
Matthew L Forister, Stephen H Jenkins
Variation in diet breadth among organisms is a pervasive feature of the natural world that has resisted general explanation. In particular, trade-offs in the ability to use one resource at the expense of another have been expected but rarely detected. We explore a spatial model for the evolution of specialization, motivated by studies of plant-feeding insects. The model is neutral with respect to the causes and consequences of diet breadth: the number of hosts utilized is not constrained by trade-offs, and specialization or generalization does not confer a direct advantage with respect to the persistence of populations or the probability of diversification...
August 2017: American Naturalist
https://www.readbyqxmd.com/read/28731760/steady-states-of-infinite-size-dissipative-quantum-chains-via-imaginary-time-evolution
#11
Adil A Gangat, Te I, Ying-Jer Kao
Directly in the thermodynamic limit, we show how to combine local imaginary and real-time evolution of tensor networks to efficiently and accurately find the nonequilibrium steady states (NESSs) of one-dimensional dissipative quantum lattices governed by a local Lindblad master equation. The imaginary time evolution first bypasses any highly correlated portions of the real-time evolution trajectory by directly converging to the weakly correlated subspace of the NESS, after which, real-time evolution completes the convergence to the NESS with high accuracy...
July 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28731352/exploiting-the-marangoni-effect-to-initiate-instabilities-and-direct-the-assembly-of-liquid-metal-filaments
#12
Christopher A Hartnett, Ivana Seric, Kyle Mahady, Lou Kondic, Shahriar Afkhami, Jason Fowlkes, Philip D Rack
The utilization of the Marangoni effect in a liquid metal is investigated, focusing on initiating instabilities to direct material assembly via the Rayleigh-Plateau instability. Thin (2 nm) copper (Cu) films are lithographically patterned onto thick (12 nm) nickel (Ni) strips to induce a surface energy gradient at the maximum wavelength of the filament instability predicted by Rayleigh-Plateau instability analysis. The pattern is irradiated with an 18 ns pulsed-laser such that the pattern melts and the resultant Ni-Cu surface tension gradient induces Marangoni flows due to the difference in surface energies...
July 21, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
https://www.readbyqxmd.com/read/28730410/engineering-of-the-cytochrome-p450-monooxygenase-system-for-benzyl-maltol-hydroxylation
#13
Iori Kozono, Kousuke Mihara, Kazuyuki Minagawa, Makoto Hibi, Jun Ogawa
Maltol derivatives are utilized in a variety of fields due to their metal-chelating abilities, and modification of the 2-methyl side chain is known to effectively expand their functional diversity. In the present study, microbial enzymes were screened for hydroxylating activity towards the 2-methyl group in a maltol derivative, 3-benzyloxy-2-methyl-4-pyrone (BMAL). Novosphingobium sp. SB32149 was found to have the ability to convert BMAL into 3-benzyloxy-2-hydroxymethyl-4-pyrone (BMAL-OH). The enzymes responsible, a cytochrome P450 monooxygenase (P450nov), a ferredoxin (FDXnov), and a ferredoxin reductase (FDRnov), were identified in the SB32149 strain...
July 20, 2017: Applied Microbiology and Biotechnology
https://www.readbyqxmd.com/read/28729688/improved-genome-recovery-and-integrated-cell-size-analyses-of-individual-uncultured-microbial-cells-and-viral-particles
#14
Ramunas Stepanauskas, Elizabeth A Fergusson, Joseph Brown, Nicole J Poulton, Ben Tupper, Jessica M Labonté, Eric D Becraft, Julia M Brown, Maria G Pachiadaki, Tadas Povilaitis, Brian P Thompson, Corianna J Mascena, Wendy K Bellows, Arvydas Lubys
Microbial single-cell genomics can be used to provide insights into the metabolic potential, interactions, and evolution of uncultured microorganisms. Here we present WGA-X, a method based on multiple displacement amplification of DNA that utilizes a thermostable mutant of the phi29 polymerase. WGA-X enhances genome recovery from individual microbial cells and viral particles while maintaining ease of use and scalability. The greatest improvements are observed when amplifying high G+C content templates, such as those belonging to the predominant bacteria in agricultural soils...
July 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/28729671/linking-rheology-and-printability-for-dense-and-strong-ceramics-by-direct-ink-writing
#15
Amin M'Barki, Lydéric Bocquet, Adam Stevenson
Direct ink writing of dense and strong ceramic objects remains an important open challenge. We develop a universal dimensionless criterion for printing such objects. Boehmite, an Al2O3 precursor, was used to assess the rheological properties leading to dense structures in ceramics manufactured by direct ink writing. Boehmite suspensions undergo time dependent gelation, thus providing a rheological laboratory of flow behaviours that can be correlated with printability requirements. We measured the evolution of rheological properties over several days and quantified the deformation of simple printed shapes at different aging times...
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28729665/identification-of-proteins-that-specifically-recognize-and-bind-protofibrillar-aggregates-of-amyloid-%C3%AE
#16
Elisabet Wahlberg, M Mahafuzur Rahman, Hanna Lindberg, Elin Gunneriusson, Benjamin Schmuck, Christofer Lendel, Mats Sandgren, John Löfblom, Stefan Ståhl, Torleif Härd
Protofibrils of the 42 amino acids long amyloid-β peptide are transient pre-fibrillar intermediates in the process of peptide aggregation into amyloid plaques and are thought to play a critical role in the pathology of Alzheimer's disease. Hence, there is a need for research reagents and potential diagnostic reagents for detection and imaging of such aggregates. Here we describe an in vitro selection of Affibody molecules that bind to protofibrils of Aβ42cc, which is a stable engineered mimic of wild type Aβ42 protofibrils...
July 20, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28729383/definitions-and-end-points-for-interventional-studies-for-arteriovenous-dialysis-access
#17
Gerald A Beathard, Charmaine E Lok, Marc H Glickman, Ahmed A Al-Jaishi, Donna Bednarski, David L Cull, Jeffery H Lawson, Timmy C Lee, Vandana D Niyyar, Donna Syracuse, Scott O Trerotola, Prabir Roy-Chaudhury, Surendra Shenoy, Margo Underwood, Haimanot Wasse, Karen Woo, Theodore H Yuo, Thomas S Huber
This paper is part of the Clinical Trial Endpoints for Dialysis Vascular Access Project of the American Society of Nephrology Kidney Health Initiative. The purpose of this project is to promote research in vascular access by clarifying trial end points which would be best suited to inform decisions in those situations in which supportive clinical data are required. The focus of a portion of the project is directed toward arteriovenous access. There is a potential for interventional studies to be directed toward any of the events that may be associated with an arteriovenous access' evolution throughout its life cycle, which has been divided into five distinct phases...
July 20, 2017: Clinical Journal of the American Society of Nephrology: CJASN
https://www.readbyqxmd.com/read/28728997/sepsis-reconsidered-identifying-novel-metrics-for-behavioral-landscape-characterization-with-a-high-performance-computing-implementation-of-an-agent-based-model
#18
Chase Cockrell, Gary An
OBJECTIVES: Sepsis affects nearly 1 million people in the United States per year, has a mortality rate of 28-50% and requires more than $20 billion a year in hospital costs. Over a quarter century of research has not yielded a single reliable diagnostic test or a directed therapeutic agent for sepsis. Central to this insufficiency is the fact that sepsis remains a clinical/physiological diagnosis representing a multitude of molecularly heterogeneous pathological trajectories. Advances in computational capabilities offered by High Performance Computing (HPC) platforms call for an evolution in the investigation of sepsis to attempt to define the boundaries of traditional research (bench, clinical and computational) through the use of computational proxy models...
July 17, 2017: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/28727736/persistent-damaged-bases-in-dna-allow-mutagenic-break-repair-in-escherichia-coli
#19
Jessica M Moore, Raul Correa, Susan M Rosenberg, P J Hastings
Bacteria, yeast and human cancer cells possess mechanisms of mutagenesis upregulated by stress responses. Stress-inducible mutagenesis potentially accelerates adaptation, and may provide important models for mutagenesis that drives cancers, host pathogen interactions, antibiotic resistance and possibly much of evolution generally. In Escherichia coli repair of double-strand breaks (DSBs) becomes mutagenic, using low-fidelity DNA polymerases under the control of the SOS DNA-damage response and RpoS general stress response, which upregulate and allow the action of error-prone DNA polymerases IV (DinB), II and V to make mutations during repair...
July 20, 2017: PLoS Genetics
https://www.readbyqxmd.com/read/28727411/one-step-synthesis-of-anti-oxidative-graphene-wrapped-copper-nanoparticles-on-flexible-substrates-for-electronic-and-electro-catalytic-applications
#20
Chi-Ang Tseng, Chiao-Chen Chen, Rajesh Kumar Ulaganathan, Chuan-Pei Lee, Hsu-Cheng Chiang, Chin-Fu Chang, Yit-Tsong Chen
In this study, we report a novel, one-step synthesis method to fabricate multi-layer graphene (MLG)-wrapped copper nanoparticles (CuNPs) directly on various substrates (e.g., polyimide film (PI), carbon cloth (CC)) or Si wafer (Si)). The electrical resistivities of the pristine MLG-CuNPs/PI and MLG-CuNPs/Si were measured 1.7 × 10(-6) and 1.4 × 10(-6) Ω·m, respectively, of which both values are ~100-fold lower than earlier reports. The MLG shell could remarkably prevent the Cu nanocore from serious damages after MLG-CuNPs being exposed to various harsh conditions...
July 20, 2017: ACS Applied Materials & Interfaces
keyword
keyword
25222
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"