3,868 research outputs found
Russkij formalizm i eksperimental'naja avtobiograficheskaja proza Andreja Belogo
No full textIl presente articolo è dedicato allo studio delle strategie di autorappresentazione messe in atto da Andrej Belyj nel ciclo "Epopeja" ("Kotik Letaev", 1918; "Krescenyj kitaec", 1921; "Zapiski cudaka", 1922), interpretate attraverso il prisma teorico delineato dai formalisti russi. Particolare attenzione è dedicata all'apparato paratestuale e alla costruzione "ad anello" della trilogia
Translation of Levchenko, N. G. 1962. Dynamics of an infection by \u3ci\u3eSarcocystis tenella\u3c/i\u3e sarcosporidia in sheep in southeast Kazakhstan [= Dinamika zarazheniya sarkosporidyami \u3ci\u3eSarcocystis tenella\u3c/i\u3e ovets yugo-vostoka Kazakhstana]. In Boev., S. N., et al., editors. \u3ci\u3eParasites of farm animals in Kazakhstan\u3c/i\u3e, I. [= \u3ci\u3eParazity sel\u27skhokzyaistvennykh zhivotnykh Kazakhstana\u3c/i\u3e, I]. \u3ci\u3eIzdat. Akademie Nauk Kazakh SSR\u3c/i\u3e, Alma-Ata, Kazakh SSR, pp. 63-68
No full textConclusions
Sarcocystis tenellainfects sheep in southeast Kazakhstan starting in their second month of life. As the sheep age the extent and intensity of infection grows, by the tenth or eleventh month, 100% of the sheep are infected. Adult sheep more than 5 years old are all infected with sarcosporidia.
As the level of fatness decreases the extent and severity of sarcosporidial infection rises.
Females become infected oftener and more heavily than males.
Infection of sheep by sarcosporidia occurs throughout the year in southeast Kazakhstan, with a rise in the spring-summer and early autumn periods; its prevalence is somewhat less in the late autumn and winter.
Translation number 23, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, United States, December 17, 1969 (6 pages)
Translation of Levchenko, N. G. 1962. Dynamics of an infection by Sarcocystis tenella sarcosporidia in sheep in southeast Kazakhstan [= Dinamika zarazheniya sarkosporidyami Sarcocystis tenella ovets yugo-vostoka Kazakhstana]. In Boev., S. N., et al., editors. Parasites of farm animals in Kazakhstan, I. [= Parazity sel\u27skhokzyaistvennykh zhivotnykh Kazakhstana, I]. Izdat. Akademie Nauk Kazakh SSR, Alma-Ata, Kazakh SSR, pp. 63-68
Translated from Russian to English by Frederick K. Plous, Jr., and edited by Norman D. Levine (notated NDL:cml
Self-organized quantum dot arrays : kinetic mapping of adatom capture
No full textDeterministic synthesis of self-organized quantum dot arrays for renewable energy, biomedical, and optoelectronic applications requires control over adatom capture zones, which are presently mapped using unphysical geometric tessellation. In contrast, the proposed kinetic mapping is based on simulated two-dimensional adatom fluxes in the array and includes the effects of nucleation, dissolution, coalescence, and process parameters such as surface temperature and deposition rate. This approach is generic and can be used to control the nanoarray development in various practical applications. © 2009 American Institute of Physics
All Local Music Yule Log
No full textMusic performed by Kara Levchenko, Sic ‘Em Buster, Bad Robot Jones, Doogie Whittaker, Two Truths, Soul Witness, Premila Mistry and Laura Guli, Emily Hall, Seth Kibel, Damon Foreman, King Soul, The Treading Lemmings, and The Airport 77s, Arlington Presbyterian Church Choir and Abby Madden.Christmas Special with all local music from the Washington DC region: In order of appearance, Kara Levchenko, Sic ‘Em Buster, Bad Robot Jones, Doogie Whittaker, Two Truths, Soul Witness, Premila Mistry and Laura Guli, Emily Hall, Seth Kibel, Damon Foreman, King Soul, The Treading Lemmings, and The Airport 77s, Arlington Presbyterian Church Choir and Abby Madden.https://ihppod.libsyn.com/all-local-music-yule-lo
Palladium-Based Contacts on p-GaN and Their Application in Laser Diodes
No full textPalladium-Based Contacts on p-GaN and Their Application in Laser Diodes. Iryna Levchenko, Serhii Kryvyi, Eliana Kamińska, Szymon Grzanka, Ewa Grzanka, Łucja Marona and Piotr Perlin. Materials 2023, 16(19), 6568; https://doi.org/10.3390/ma16196568In this paper, we investigate the effect of Pd thickness and heat treatment on Pd/Ni/Au/p-GaN metal contacts. The as-deposited samples exhibit a smooth morphology and non-linear I–V characteristics. Heat treatment in a N2 atmosphere leads to degradation of the contact microstructure, resulting in diffusion of Ga, void formation on the interface and mixing of metals. Annealing in a mixture of N2 and O2 improves adhesion and reduces contact resistance. However, this process also induces GaN decomposition and species mixing. The mixing of metal–Ga and metal–metal remains unaffected by the method of thermal treatment but depends on gas composition for thin Pd contacts. To achieve low-resistance contacts (≈1 × 10−4 Ω cm2), we found that increasing the Pd thickness and using N2 + O2 as the annealing environment are effective measures. Nevertheless, the degradation effect of the annealed contact microstructure in the form of the void generation becomes evident as the thickness of Pd increases. Laser diodes (LDs) with optimized palladium-based contacts operate at a voltage of 4.1 V and a current density of 3.3 kA/cm².The names of files correspond to the nnumbering of the figures in the paper. It includes:Figure 1. SEM image of the surface of as-deposited Pd/Ni/Au (10/10/30 nm) metallization on p-GaN. The provided layer thicknesses correspond to the settings used for evaporation.Figure 2. XRD profile for investigated Pd/Ni/Au (10/10/30 nm) as-grown sample. The powder diffraction patterns with corresponding reference numbers in PDF-2 and ICSD databases are shown.Figure 3. HR-STEM image (a) of as-deposited Pd/Ni/Au (10/10/30 nm) together with the interplanar distance for the indicated lattice planes (b) determined from measurements by FFT. ZA—zone axis.Figure 4. Crystallographic orientation of GaN (a) and metal layers (b,c).Figure 5. I−V plots for the as-deposited and annealed contacts.Figure 6. SEM (a) and STEM (b) images of Pd/Ni/Au (10/10/30 nm) annealed in RTA in N2 flow at 530 °C.Figure 7. EDX elemental mapping data for p-GaN/Pd/Ni/Au (10/10/30 nm) contact annealed in N2 (a–f). Schematic view of the contact composition (g).Figure 8. XRD profiles for investigated as-grown sample and after annealing in N2.Figure 9. SEM data of Pd/Ni/Au (10/10/30 nm) annealed in RTA in N2 + O2 flow at 530 °C.Figure 10. EDX elemental mapping data (a–f) and schematic view (g) of Pd/Ni/Au (10/10/30 nm) annealed in RTA in N2 + O2 flow at 530 °C.Figure 11. XRD profiles for investigated as-grown sample after annealing by RTA in N2 + O2 flow.Figure 12. SEM data of Pd/Ni/Au (90/10/30 nm) after annealing by (a) oven in N2 + O2 + H2O and (b) RTA in N2 + O2.Figure 13. EDX maps of Pd/Ni/Au (90/10/30 nm) after annealing by oven in N2 + O2 + H2O (a–f) and scheme of Pd/Ni/Au (90/10/30 nm) composition (g).Figure 14. XRD profiles for investigated as-grown sample and after annealing.</p
Nanostructures of various dimensionalities from plasma and neutral fluxes
No full textA complex multi-scale model and numerical simulations are used to demonstrate, by simulating the development of patterns of nanotips, nanowalls, nanoislands and nanovoids of a characteristic size of 5-100 nm, a greater degree of determinism in the formation of various nanostructures by using the low-density, low-temperature plasma-based processes. It is shown that in the plasma, in contrast to the neutral gas-based processes, one can synthesize nanostructures of various dimensionalities and shapes with a larger surface density, desired geometrical parameters and narrower size distribution functions. This effect is mainly attributed to strong ion focusing by irregular electric fields in the nanopatterns, which effectively redistributes the influxes of plasma-generated building units and thus provides a selective control of their delivery to the growing nanostructures
New generation of lithium-air energy storage systems
No full textQuesta tesi analizza lo sviluppo di batterie litio-aria (Li–O2) come alternativa alle tradizionali batterie agli ioni di litio. L'attenzione è focalizzata sull'innovazione dei materiali per anodi e catodi, nonché sull'ottimizzazione degli elettroliti, al fine di soddisfare le crescenti esigenze energetiche della società contemporanea e promuovere la sostenibilità. Le batterie Li–O2 offrono un’elevata densità energetica teorica e potenziali benefici ambientali; tuttavia, la loro applicazione pratica è ostacolata dall’instabilità dell’anodo e dell’elettrolita, oltre alla limitata durata del ciclo di vita. Il presente studio affronta queste problematiche mediante la sintesi di nuovi materiali e il perfezionamento dei componenti della batteria, con l’obiettivo di migliorarne le prestazioni e la durabilità.
Il lavoro inizia dallo studio di anodo nanostrutturato Sn@C come alternativa al litio metallico, con l’obiettivo di mitigare la formazione di dendriti. Il composito Sn@C, costituito da nanoparticelle di stagno disperse in una matrice di carbonio, si distingue per un’eccellente ritenzione della capacità, un’elevata densità energetica e una vita utile che si estende fino a 300 cicli, con ridotta polarizzazione e un’efficienza coulombica prossima al 100%, confermando il potenziale del materiale come candidato promettente per batterie di nuova generazione.
L’accoppiamento con un catodo spinello (LiNi0.35Cu0.1Mn1.45Al0.1O4) consente la realizzazione di una cella agli ioni di litio con una tensione operativa media di 4,3 V e una densità energetica teorica prossima a 500 Wh/kg, con un valore densità energia pratica di 165 Wh/kg.
Per migliorare le prestazioni delle batterie Li–O2, è stata condotta un’analisi approfondita dei gas diffusion layer (GDL) a base di carbonio, valutandone la morfologia, la porosità e le proprietà strutturali. Successivamente, il GDL 39BB è stato ricoperto con un composito di nanotubi di carbonio e Few Layer Graphene, ottenendo una cella con una durata superiore a 100 cicli a una capacità di 500 mAh g−1.
L’attenzione è stata successivamente rivolta all’ottimizzazione dei materiali catodici, basati su MWCNTs e FLG in diverse proporzioni, con l’aggiunta di un catalizzatore a base di oro nanometrico. Questa configurazione ha consentito un significativo miglioramento della reversibilità e della cinetica delle reazioni elettrochimiche dell’ossigeno, garantendo una maggiore stabilità del sistema e un incremento dell’output energetico. Il materiale catodico più performante, costituito da MWCNTs e FLG in rapporto 50:50, con l’aggiunta dell’8% di Au, ha raggiunto una capacità di 954 mAh g−1, mantenendo un’efficienza coulombica del 100% per oltre 70 cicli.
Sono stati inoltre sviluppati elettroliti a base di PEGDME 250, combinato con i sali LiTFSI e LiNO3, con l’obiettivo di ottenere soluzioni elettrolitiche più stabili ed ecosostenibili. Le formulazioni risultanti presentano eccellente stabilità termica, un’ampia finestra elettrochimica, elevata conducibilità ionica e un numero di trasferimento adeguato.
Infine, è stata sviluppata, come proof-of-concept, una cella Li-ione/O2 che integra l’anodo Sn@C, il catodo MWCNT/FLG 50:50 e gli elettroliti a base di PEGDME 250.I risultati preliminari evidenziano che la cella con elettrolita privo di LiNO3 ha raggiunto una capacità specifica di 350 mAh g−1, mentre la cella contenente LiNO3 ha raggiunto una capacità specifica di 275 mAh g−1.
Il presente studio fornisce un contributo significativo allo sviluppo di materiali elettrodici ed elettroliti ad alte prestazioni, favorendo il progresso dei sistemi di accumulo elettrochimico. Le innovazioni proposte delineano un percorso promettente verso soluzioni di accumulo energetico più sostenibili, scalabili ed economicamente vantaggiose, agevolando l’integrazione delle fonti rinnovabili e il progresso della mobilità elettrica.This thesis examines the development of advanced lithium-air (Li–O2) battery systems as an alternative to conventional lithium-ion batteries. It focuses on the investigation of innovative anode and cathode materials, as well as optimized electrolytes, to address the growing energy demands of modern society while fostering sustainability.
Li–O2 batteries hold significant promise due to their high theoretical energy density and environmental advantages.
However, their practical application is constrained by challenges such as anode instability, electrolyte degradation, and limited cycle life.
This work seeks to address these obstacles through the synthesis of novel materials and the optimization of battery components to achieve enhanced performance and durability.
The study introduces a nanostructured Sn@C alloying anode as a replacement for lithium metal, addressing issues related to dendrite formation, which pose safety risks and limit cycling life.
The Sn@C composite, consisting of tin nanoparticles embedded within a carbon matrix, exhibits excellent capacity retention, high tap density, and a cycle life of up to 300 cycles. Electrochemical analysis demonstrates reduced polarization and a charge-discharge efficiency nearing 100%, positioning it as a promising candidate for next-generation batteries.
When combined with a high-voltage spinel cathode, LiNi0.35Cu0.1Mn1.45 Al0.1O4, the resulting Li-ion full cell achieves an average working voltage of 4.3 V and an energy density approaching 500 Wh/kg, with practical outputs of 165 Wh/kg.
A comprehensive evaluation of carbon-based gas diffusion layers (GDLs) was conducted to improve the performance of Li–O2 batteries.
GDLs with varying morphology, porosity, and structural properties were characterized and tested to assess their influence on ion diffusion kinetics and electrode stability.
Then GDL 36BB was subsequently coated with a composite of Multi Walled Carbon Nanotubes (MWCNTs) and Few Layer Graphene (FLG), resulting in a cell that demonstrated a lifespan exceeding 100 cycles at a capacity of 500 mAh g-1.
The research subsequently focuses on improving cathode materials composed of MWCNTs and Few- FLG in various ratios, further enhanced with nanometric gold catalysts.
This configuration markedly improves the reversibility and kinetics of oxygen electrochemical reactions, enabling stable cycling and increased energy output.
The most effective cathodic material, comprising a 50:50 ratio of MWCNTs and FLG, with addition of 8% Au catalyst, achieves a cell capacity of 954 mAh g-1, sustained over 70 cycles with 100% efficiency.
Electrolytes based on PEGDME 250 with LiTFSI and LiNO3 salts have been developed to achieve greener and more stable electrolyte solutions.
These formulations exhibit excellent thermal stability, ranging from -50 °C to 200 °C, a broad electrochemical window, high ionic conductivity, an appropriate transference number (~0.6 for both electrolytes), and facilitate the formation of a robust solid electrolyte interphase (SEI).
Finally, a proof-of-concept Li-ion/O2 cell was developed, incorporating the Sn@C anode, the MWCNT/FLG 50:50 cathode, and PEGDME 250-based electrolytes.
Preliminary results demonstrated that the cell with a LiNO3-free electrolyte achieved a capacity of 350 mAh g-1 while the cell containing LiNO3 exhibited a capacity of 275 mAh g-1, both cells with a lifecycle of 40 cycles.
This comprehensive study provides critical insights into the development of high-performance and environmentally friendly electrode materials and electrolytes for lithium-air batteries, contributing to the advancement of electrochemical energy storage systems.
The innovations presented herein represent a promising pathway toward cost-effective, sustainable, and scalable battery solutions, enabling greater integration of renewable energy and supporting the growth of electric mobility
Simulation of ion flux distribution in conductive and nonconductive nanotip patterns
No full textThe distribution of flux of carbon-bearing cations over nanopatterned surfaces with conductive nanotips and nonconductive nanoislands is simulated using the Monte-Carlo technique. It is shown that the ion current is focused to nanotip surfaces when the negative substrate bias is low and only slightly perturbed at higher substrate biases. In the low-bias case, the mean horizontal ion displacement caused by the nanotip electric field exceeds 10 nm. However, at higher substrate biases, this value reduces down to 2 nm. In the nonconductive nanopattern case, the ion current distribution is highly nonuniform, with distinctive zones of depleted current density around the nanoislands. The simulation results suggest the efficient means to control ion fluxes in plasma-aided nanofabrication of ordered nanopatterns, such as nanotip microemitter structures and quantum dot or nanoparticle arrays. © World Scientific Publishing Company
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