253 research outputs found
Dynamical, structural and chemical heterogeneities in a binary metallic glass-forming liquid
As approaching the glass transition, particle motion in liquids becomes
highly heterogeneous and regions with virtually no mobility coexist with
liquid-like domains. This complex dynamics is believed to be responsible for
different phenomena including non-exponential relaxation and the breakdown of
Stokes-Einstein relation. Understanding the relationships between dynamical
heterogeneities and local structure in metallic liquids and glasses is a major
scientific challenge. Here we use classical molecular dynamics simulations to
study the atomic dynamics and microscopic structure of
\mbox{Cu}_{50}\mbox{Zr}_{50} alloy in the supercooling regime. Dynamical
heterogeneities are identified via an isoconfigurational analysis. As deeper
supercooling is achieved a transition from isolated to clustering low mobility
atoms is reported. These slow clusters, whose size grow upon cooling, are also
associated to concentration fluctuations, characterized by a Zr-enriched phase,
with a composition \mbox{CuZr}_2. In addition, a structural analysis of slow
clusters based on Voronoi tessellation evidences an increase with respect of
the bulk system of the fraction of Cu atoms having a local icosahedral order.
These results are in agreement with the consolidated scenario of the relevant
role played by icosahedral order in the dynamic slowing-down in supercooled
metal alloys
Growth of graphene on 6H-SiC by molecular dynamics simulation
Classical molecular-dynamics simulations were carried out to study epitaxial
growth of graphene on 6H-SiC(0001) substrate. It was found that there exists a
threshold annealing temperature above which we observe formation of graphitic
structure on the substrate. To check the sensitivity of the simulation results,
we tested two empirical potentials and evaluated their reliability by the
calculated characteristics of graphene, its carbon-carbon bond-length, pair
correlation function, and binding energy.Comment: 7 pages, 5 figure
Effects of three-body interactions on the structure and thermodynamics of liquid krypton
Large-scale molecular dynamics simulations are performed to predict the
structural and thermodynamic properties of liquid krypton using a potential
energy function based on the two-body potential of Aziz and Slaman plus the
triple-dipole Axilrod-Teller (AT) potential. By varying the strength of the AT
potential we study the influence of three-body contribution beyond the
triple-dipole dispersion. It is seen that the AT potential gives an overall
good description of liquid Kr, though other contributions such as higher order
three-body dispersion and exchange terms cannot be ignored.Comment: 11 pages, 3 figures, LaTeX, to appear in J. Chem. Phy
Highly variable AFLP and S-SAP markers for the identification of ‘Malbec’ and ‘Syrah’ clones
The retrotransposon-based sequence-specific amplification polymorphism (S-SAP) and the amplified fragment length polymorphism (AFLP) marker systems were used to assess the clonal variation of 14 ‘Syrah’ and 22 ‘Malbec’ (Vitis vinifera L.) clones. The utility of S-SAP markers was compared to that of AFLP markers. On the basis of our results, S-SAP is more informative marker system and showed higher average number of polymorphic bands per cultivar group than AFLP. Relationships among clones were analyzed by cluster analysis using unweighted pair-groups using arithmetic averages and in both cases revealed well defined groups of clones, in which ‘Malbec’ clones were separated from ‘Syrah’ clones. High variability of some clones could also be seen within these clusters. The different levels of polymorphism for ‘Malbec’ and ‘Syrah’ obtained in this study suggest that ‘Malbec’ exhibits a higher mutation frequency than ‘Syrah’. Our results indicate that higher proportion of polymorphic bands in S-SAP makes it a less labour-intensive and more efficient approach for developing markers for clonal identification.
Highly variable AFLP and S-SAP markers for the identification of "Malbec" and "Syrah" clones
The retrotransposon-based sequence-specific amplification polymorphism (S-SAP) and the amplified fragment length polymorphism (AFLP) marker systems were used to assess the clonal variation of 14 ‘Syrah’ and 22 ‘Malbec’ (Vitis vinifera L.) clones. The utility of S-SAP markers was compared to that of AFLP markers. On the basis of our results, S-SAP is more informative marker system and showed higher average number of polymorphic bands per cultivar group than AFLP. Relationships among clones were analyzed by cluster analysis using unweighted pair-groups using arithmetic averages and in both cases revealed well defined groups of clones, in which ‘Malbec’ clones were separated from ‘Syrah’ clones. High variability of some clones could also be seen within these clusters. The different levels of polymorphism for ‘Malbec’ and ‘Syrah’ obtained in this study suggest that ‘Malbec’ exhibits a higher mutation frequency than ‘Syrah’. Our results indicate that higher proportion of polymorphic bands in S-SAP makes it a less labour-intensive and more efficient approach for developing markers for clonal identification.Fil: Stajner, N.. University of Ljubljana; EsloveniaFil: Jakse, J.. University of Ljubljana; EsloveniaFil: Javornik, B.. University of Ljubljana; EsloveniaFil: Masuelli, Ricardo Williams. Instituto Nacional de Tecnología Agropecuaria. Centro Regional Mendoza-san Juan. Estación Experimental Agropecuaria la Consulta. Agencia de Extensión Rural la Consulta; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias; ArgentinaFil: Martínez, Liliana Estela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Biología Agrícola de Mendoza. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Instituto de Biología Agrícola de Mendoza; Argentin
Повышение урожайности в АПК с учетом инноваций и других факторов
В статье подняты актуальные вопросы продовольственной безопасности страны при существующих санкциях. Трудности импортозамещения рассмотрены в рамках российского агропромышленного комплекса (АПК). Обозначены существующие проблемы в сельскохозяйственном секторе экономике и предложены пути их преодоления. Исследованы направления инноваций в сельском хозяйстве, эффективные технологии в АПК, а также факторы, сдерживающие их внедрение в производство. Даны рекомендации доведения инноваций до производства.The article raised topical issues of food security of the country under existing sanctions. Difficulties of import substitution were considered within the framework of the Russian agroindustrial complex (AIC). The article identified the existing problems in the agricultural sector of the economy and proposed ways to overcome them. The directions of innovations in agriculture, effective technologies in the agroindustrial complex, as well as the factors that inhibit their introduction into production are studied. There are given recommendations for bringing innovations to production
Three-body interactions in colloidal systems
We present the first direct measurement of three-body interactions in a
colloidal system comprised of three charged colloidal particles. Two of the
particles have been confined by means of a scanned laser tweezers to a
line-shaped optical trap where they diffused due to thermal fluctuations. Upon
the approach of a third particle, attractive three-body interactions have been
observed. The results are in qualitative agreement with additionally performed
nonlinear Poissson-Boltzmann calculations, which also allow us to investigate
the microionic density distributions in the neighborhood of the interacting
colloidal particles
Increased frequency and nocturia in a middle aged male may not always be due to Benign Prostatic Hypertrophy (BPH): a case report
Primary signet ring cell carcinoma of urinary bladder is a rare type of bladder tumor and carries a very high mortality rate. It may have a clinical presentation similar to common diseases like Benign Prostatic Hypertrophy (BPH) and the management options are extremely limited. We report a case of 58 year old Caucasian male who presented with a 5 month history of increased frequency of urination, nocturia and weight loss without any fever or hematuria. He was found to have an increased creatinine of 2.8 mg/dl and a prostate specific antigen level of 0.18 ng/ml. His azotemia was thought to be secondary to BPH. A foley catheter was initially placed with a plan for outpatient follow up. On removal of the catheter his problems persisted and he returned to the hospital. Diagnostic work up including abdominal ultrasonography, computed tomography (CT) scan, retrograde pyelogram, cystography and cystoscopic biopsies revealed the diagnosis of primary signet ring cell carcinoma of urinary bladder. Although cystectomy was planned, our patient passed away before this could be done
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