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H Tetlow, D Curcio, A Baraldi, L Kantorovich
The kinetics of the thermal decomposition of hydrocarbons on the Ir(111) surface is determined using kinetic Monte Carlo (kMC) and rate equations simulations, both based on the density functional theory (DFT) calculated energy barriers of the involved reaction processes. This decomposition process is important for understanding the early stages of epitaxial graphene growth where the deposited hydrocarbon acts as a carbon feedstock for graphene formation. The methodology of the kMC simulations and the rate equation approaches is discussed and a comparison between the results obtained from both approaches is made in the case of the temperature programmed decomposition of ethylene for different initial coverages...
January 5, 2018: Physical Chemistry Chemical Physics: PCCP
Hamza M Ruzayqat, Tim P Schulze
We introduce a new kinetic Monte Carlo (KMC) algorithm for off-lattice simulation. In off-lattice KMC one needs to calculate the rates for all possible moves from the current state by searching the energy landscape for index-1 saddle points surrounding the current basin of attraction. We introduce a rejection scheme where the true rates are replaced by rate estimates. This is done by first associating each saddle point with the atom that would move the most if that transition were to take place, then constructing an estimate for the total rate associated with each atom by using a nearest-neighbor bond count...
December 6, 2017: Journal of Chemical Theory and Computation
Sholihatul Amaliya, Yeni Rustina, Nur Agustini
Kangaroo mother care (KMC) is an evidence-based approach that has been scientifically proven to have a positive effect on mothers and infants. One of the barriers to performing KMC at home is the absence of a special KMC carrier. The most widely used KMC carriers in Indonesia are kangaroo pouch, thari, wrap and traditional wraps in the form of a long strip of fabric. This study's aim was to compare the level of maternal comfort when performing KMC with three different KMC carriers. The study used crossover design involving 20 mothers with low birth weight (LBW) infants as responders, selected through a consecutive sampling method...
2017: Comprehensive Child and Adolescent Nursing
Eleni Kenanga Purbasary, Yeni Rustina, Tri Budiarti
Mothers giving birth to low birth weight babies (LBWBs) have low confidence in caring for their babies because they are often still young and may lack the knowledge, experience, and ability to care for the baby. This research aims to determine the effect of education about kangaroo mother care (KMC) on the confidence and ability of young mothers to implement KMC. The research methodology used was a controlled-random experimental approach with pre- and post-test equivalent groups of 13 mothers and their LBWBs in the intervention group and 13 mothers and their LBWBs in the control group...
2017: Comprehensive Child and Adolescent Nursing
Laleh Goudarzvand, Akram Dabirian, Manizheh Nourian, Hadi Jafarianesh, Mehdi Ranjbaran
BACKGROUND: One of the adjuvant and desirable therapies is skin contact between mother and baby or Kangaroo mother care (KMC) that is a cheap, accessible, relaxing, noninvasive and easy method. This study aimed to compare the effect of conventional phototherapy method and phototherapy along with KMC on cutaneous bilirubin in neonates with physiological jaundice. MATERIALS AND METHODS: In this randomized clinical trial, all infants with physiological jaundice who referred for phototherapy to Mofid Hospital of Shahid Beheshti University of Medical Sciences, Tehran, Iran were selected by convenience sampling based on inclusion criteria and were randomly assigned into two groups of conventional phototherapy (n = 35) and phototherapy along with KMC (n = 35)...
November 12, 2017: Journal of Maternal-fetal & Neonatal Medicine
M Núñez, T Robie, D G Vlachos
Kinetic Monte Carlo (KMC) simulation provides insights into catalytic reactions unobtainable with either experiments or mean-field microkinetic models. Sensitivity analysis of KMC models assesses the robustness of the predictions to parametric perturbations and identifies rate determining steps in a chemical reaction network. Stiffness in the chemical reaction network, a ubiquitous feature, demands lengthy run times for KMC models and renders efficient sensitivity analysis based on the likelihood ratio method unusable...
October 28, 2017: Journal of Chemical Physics
Giridhar Nandipati, Xiujuan Jiang, Rama S Vemuri, Suveen Mathaudhu, Aashish Rohatgi
Si-atom and vacancy diffusion in α-Fe-Si alloys in the ferromagnetic state, with and without magnetic order and in various temperature ranges, is studied using AKSOME, an on-lattice self-learning KMC code. Si-atom diffusion in the dilute limit and vacancy diffusion in A2- phase of the α-Fe-Si alloy up to Si concentrations of 12at.% is studied in the temperature range of 350-700 K and 350-500 K, respectively. Local Si-atom neighborhood dependent activation energies for vacancy hops were calculated on-the-fly using a broken-bond model based on pairwise interaction...
November 1, 2017: Journal of Physics. Condensed Matter: An Institute of Physics Journal
Haoyuan Li, Anton D Chavez, Huifang Li, Hong Li, William R Dichtel, Jean-Luc Bredas
The preparation of two-dimensional covalent organic frameworks (2D COFs) with large crystalline domains and controlled morphology is necessary for realizing the full potential of their atomically precise structures and uniform, tailorable porosity. Currently 2D COF syntheses are developed empirically, and most materials are isolated as insoluble and unprocessable powders with typical crystalline domain sizes smaller than 50 nm. Little is known about their nucleation and growth processes, which involve a combination of covalent bond formation, degenerate bond exchange, and noncovalent stacking processes...
November 15, 2017: Journal of the American Chemical Society
Tanya Guenther, Sarah Moxon, Bina Valsangkar, Greta Wetzel, Juan Ruiz, Kate Kerber, Hannah Blencowe, Queen Dube, Shashi N Vani, Donna Vivio, Hema Magge, Socorro De Leon-Mendoza, Janna Patterson, Goldy Mazia
BACKGROUND: As efforts to scale up the delivery of Kangaroo Mother Care (KMC) in facilities are increasing, a standardized approach to measure implementation and progress towards effective coverage is needed. Here, we describe a consensus-based approach to develop a measurement framework and identify a core set of indicators for monitoring facility-based KMC that would be feasible to measure within existing systems. METHODS: The KMC measurement framework and core list of indicators were developed through: 1) scoping exercise to identify potential indicators through literature review and requests from researchers and program implementers; and 2) face-to-face consultations with KMC and measurement experts working at country and global levels to review candidate indicators and finalize selection and definitions...
December 2017: Journal of Global Health
Mie Andersen, Craig P Plaisance, Karsten Reuter
First-principles screening studies aimed at predicting the catalytic activity of transition metal (TM) catalysts have traditionally been based on mean-field (MF) microkinetic models, which neglect the effect of spatial correlations in the adsorbate layer. Here we critically assess the accuracy of such models for the specific case of CO methanation over stepped metals by comparing to spatially resolved kinetic Monte Carlo (kMC) simulations. We find that the typical low diffusion barriers offered by metal surfaces can be significantly increased at step sites, which results in persisting correlations in the adsorbate layer...
October 21, 2017: Journal of Chemical Physics
Yangzheng Lin, Kristen A Fichthorn
We use first-principles density-functional theory to characterize the binding sites and diffusion mechanisms for a Ga adatom on the GaAs(001)β2(2 × 4) surface. Diffusion in this system is a complex process involving eleven unique binding sites and sixteen different hops between neighboring binding sites. Among the binding sites, we can identify four different superbasins such that the motion between binding sites within a superbasin is much faster than hops exiting the superbasin. To describe diffusion, we use a recently developed local superbasin kinetic Monte Carlo (LSKMC) method, which accelerates a conventional kinetic Monte Carlo (KMC) simulation by describing the superbasins as absorbing Markov chains...
October 21, 2017: Journal of Chemical Physics
Qian Yang, Carlos A Sing-Long, Evan J Reed
We propose a novel statistical learning framework for automatically and efficiently building reduced kinetic Monte Carlo (KMC) models of large-scale elementary reaction networks from data generated by a single or few molecular dynamics simulations (MD). Existing approaches for identifying species and reactions from molecular dynamics typically use bond length and duration criteria, where bond duration is a fixed parameter motivated by an understanding of bond vibrational frequencies. In contrast, we show that for highly reactive systems, bond duration should be a model parameter that is chosen to maximize the predictive power of the resulting statistical model...
August 1, 2017: Chemical Science
Sai Manoj Gali, Gabriele D'Avino, Philippe Aurel, Guangchao Han, Yuanping Yi, Theodoros A Papadopoulos, Veaceslav Coropceanu, Jean-Luc Brédas, Georges Hadziioannou, Claudio Zannoni, Luca Muccioli
We present a computational approach to model hole transport in an amorphous semiconducting fluorene-triphenylamine copolymer (TFB), which is based on the combination of molecular dynamics to predict the morphology of the oligomeric system and Kinetic Monte Carlo (KMC), parameterized with quantum chemistry calculations, to simulate hole transport. Carrying out a systematic comparison with available experimental results, we discuss the role that different transport parameters play in the KMC simulation and in particular the dynamic nature of positional and energetic disorder on the temperature and electric field dependence of charge mobility...
October 7, 2017: Journal of Chemical Physics
M Apostolopoulou, R Day, R Hull, M Stamatakis, A Striolo
The mechanism of fluid migration in porous networks continues to attract great interest. Darcy's law (phenomenological continuum theory), which is often used to describe macroscopically fluid flow through a porous material, is thought to fail in nano-channels. Transport through heterogeneous and anisotropic systems, characterized by a broad distribution of pores, occurs via a contribution of different transport mechanisms, all of which need to be accounted for. The situation is likely more complicated when immiscible fluid mixtures are present...
October 7, 2017: Journal of Chemical Physics
Grace Chan, Ilana Bergelson, Emily R Smith, Tobi Skotnes, Stephen Wall
Kangaroo Mother Care (KMC) is an evidence-based intervention that reduces neonatal morbidity and mortality. However, adoption among health systems has varied. Understanding the interaction between health system functions-leadership, financing, healthcare workers (HCWs), technologies, information and research, and service delivery-and KMC is essential to understanding KMC adoption. We present a systematic review of the barriers and enablers of KMC implementation from the perspective of health systems, with a focus on HCWs and health facilities...
December 1, 2017: Health Policy and Planning
Melissa Pike, Alta Kritzinger, Esedra Krüger
OBJECTIVE: To describe the breastfeeding characteristics of late-preterm infants (LPIs) in a kangaroo mother care (KMC) unit. MATERIALS AND METHODS: In a 20-bed KMC unit, the breastfeeding of 73 purposively-selected LPIs' (mean gestational age: 34.8 weeks) was observed once-off, using the Preterm Infant Breastfeeding Behavior Scale. Participants' mean age was 9.5 days, mean number of days in the unit was 3.1 days, and mean number of days breastfeeding was 7.5 on observation...
September 20, 2017: Breastfeeding Medicine: the Official Journal of the Academy of Breastfeeding Medicine
Girish Menon, Rajesh Nair, I K Laskhman, Vinod Kumar, G Lakshmi Prasad
Kasturba Medical College (KMC), Manipal, is the oldest and one of the most reputed medical institutes in coastal Karnataka, catering to a population of over 4 million, spanning a stretch of over 350 kms along the southwest coast of India from Mangalore to Goa. The Department of Neurosurgery at KMC, established in 1968, continues to be the leading and most preferred referral center providing high quality neurosurgical services in this region. The article provides an insight into the origin of the department, its infancy and teething troubles, its continuous growth and landmark achievements over the years...
September 2017: Neurology India
Julia-Sophia Bellingrath, G Alex Ochakovski, Immanuel P Seitz, Susanne Kohl, Eberhart Zrenner, Nicola Hanig, Holger Prokisch, Bernhard H Weber, Susan M Downes, Simon Ramsden, Robert E MacLaren, M Dominik Fischer
Purpose: Mutations in retinitis pigmentosa GTPase regulator (RPGR) cause 70% to 90% of X-linked retinitis pigmentosa (XLRP3) cases, making this gene a high-yield target for gene therapy. This study analyzed the utility of relevant clinical biomarkers to assess symmetry and rate of progression in XLRP3. Methods: A retrospective, cross-sectional analysis of 50 XLRP3 patients extracted clinical data including visual acuity (VA), visual fields (I4e and III4e targets), foveal thickness, and ERG data points alongside molecular genetic data...
September 1, 2017: Investigative Ophthalmology & Visual Science
P Matvija, F Rozbořil, P Sobotík, I Ošt'ádal, P Kocán
The state of matter in fluid phases, determined by the interactions between particles, can be characterized by a pair correlation function (PCF). At the nanoscale, the PCF has been so far obtained experimentally only by means of reciprocal-space techniques. We use scanning tunneling microscopy (STM) at room temperature in combination with lattice-gas kinetic Monte Carlo (KMC) simulations to study a two-dimensional gas of highly mobile molecules of fluorinated copper phthalocyanine on a Si(111)/Tl-(1×1) surface...
August 25, 2017: Journal of Physical Chemistry Letters
Pratik P Dholabhai, Enrique Martínez, Nicholas T Brown, Blas Pedro Uberuaga
In the quest to develop new materials with enhanced ionic conductivity for battery and fuel cell applications, nano-structured oxides have attracted attention. Experimental reports indicate that oxide heterointerfaces can lead to enhanced ionic conductivity, but these same reports cannot elucidate the origin of this enhancement, often vaguely referring to pipe diffusion at misfit dislocations as a potential explanation. However, this highlights the need to understand the role of misfit dislocation structure at semi-coherent oxide heterointerfaces in modifying carrier mobilities...
August 18, 2017: Physical Chemistry Chemical Physics: PCCP
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