The lithiation process and Li diffusion in amorphous SiO2 and Si from first-principles

Silicon is considered the next-generation, high-capacity anode for Li-ion energy storage applications, however, despite significant effort, there are still uncertainties regarding the bulk Si and surface SiO2 structural and chemical evolution as it undergoes lithiation and amorphization. In this paper, we present first-principles calculations of the evolution of the amorphous Si anode, including its oxide surface layer, as a function of Li concentration. We benchmark our methodology by comparing the results for the Si bulk to existing experimental evidence of local structure evolution, ionic diffusivity as well as electrochemical activity. Recognizing the important role of the surface Si oxide (either native or artificially grown), we undertake the same calculations for amorphous SiO2, analyzing its potential impact on the activity of Si anode materials. Derived voltage curves for the amorphous phases compare well to experimental results, highlighting that SiO2 lithiates at approximately 0.7 V higher than Si in the low Li concentration regime, which provides an important electrochemical fingerprint. The combined evidence suggests that i) the inherent diffusivity of amorphous Si is high (in the order 10−9cm2s−1 - 10−7cm2s−1), ii) SiO2 is thermodynamically driven to lithiate, such that Li–O local environments are increasingly favored as compared to Si–O bonding, iii) the ionic diffusivity of Li in LiySiO2 is initially two orders of magnitude lower than that of LiySi at low Li concentrations but increases rapidly with increasing Li content and iv) the final lithiation product of SiO2 is Li2O and highly lithiated silicides. Hence, this work suggests that - excluding explicit interactions with the electrolyte - the SiO2 surface layer presents a kinetic impediment for the lithiation of Si and a sink for Li inventory, resulting in non-reversible capacity loss through strong local Li–O bond formation

Learning from and Reflecting on Marjane Satrapi’s Persepolis II: The Story of a Return [Composition]

This staged Composition I - ENG 101 assignment in its entirety was completed over the course of approximately six weeks. Students were allowed to revise and re-submit their work along the way and the grade they earned from this module constituted 30% of their final grade for the course. In addition to being aligned with the integrative learning core competency and written ability, the assignment emphasizes advancing the students’ abilities to closely read primary and secondary sources, synthesize their understanding of these texts in their writing, and reflect on their work and learning in all the parts outlined below. While this particular assignment is scaffolded and divided into five parts completed and revised over the course of several weeks, instructors may choose to combine the different parts of this module. Instructors may also choose to grade each part separately or assign a cumulative grade. By the time the students begin Part I of this module, they will have read Marjane Satrapi’s graphic memoir Persepolis 2: The Story of a Return in its entirety and completed a number of low stakes writing assignments, which stemmed from close reading questions and class discussions. LaGuardia’s Core Competencies and Communication Abilities Main Course Learning Objectives: 1. Enable students to understand that writing is a process involving such strategies as prewriting, drafting, revising, editing and proofreading. 2. Teach students to read and listen critically and analytically, including identifying an argument’s major assumptions and assertions and evaluating its supporting evidence. 3. Teach students to write clearly and coherently in varied academic formats (such as formal essays, research papers, and reports) using standard English and appropriate technology to critique and improve one\u27s own and others\u27 texts. Essays will vary in length between 600 and 1500 words. Faculty will enable students to understand audience, voice, and purpose. 4. Guide students to acquire research skills by using appropriate technology, including gathering evaluating, and synthesizing primary and secondary sources. Faculty will teach students to utilize quotation, summation, paraphrase, and citation and to avoid plagiarism. 5. Teach students to support a thesis with well-reason arguments, and communicate persuasively over a variety of contexts, purposes, audiences, and media. 6. Guide students to formulate original ideas and relate them to the ideas of others by employing the conventions of ethical attribution and citation

Design of FLASH Memory Reliability Test System

Flash paměť je typem elektricky vymazatelné a programovatelné volatilní paměti (EEPROM). Stala se jednou z nejvýznamnějších částí trhu s polovodičovými pamětmi. Výhodou flash pamětí je, že jsou elektricky přepisovatelné jako EEPROM s jedinou tranzistorovou strukturou jako dřívější EPROM. Tato kombinace umožňuje vyrábět flash paměti s vyšší hustotou a s nižšími náklady. Zatímco tržní podíl pamětí flash vzrůstá, technologie paměti flash posouvá své fyzické limity spolehlivosti paměti kvůli škálování a neustálému namáhání. Omezená životnost programu a množství přepisů (mazání) je nejvýznamnějším problémem z hlediska spolehlivosti technologie flash. V této studii je demonstrován a testován mechanismus selhání vyvolaný stresem způsobený konstantním cyklováním programování / mazání. Následně je poskytnuto řešení pro správu dat pro produkty Eaton využívající ASIC2 čip.Flash Memory, a type of electrically erasable and programmable read-only memory (EEPROM), became one of the most significant portions in the semiconductor memory market. Flash memories have the advantage of being electrically erasable like EEPROMs with a single transistor structure like early EPROMs. This combination allows Flash to be manufactured in great densities with lower cost and providing electrically erasable functionality. While the market share of Flash memory rises, Flash memory technology is pushing its physical limits in memory reliability due to scaling and constant stress. Program/Erase endurance is the most prominent issue in terms of reliability in Flash technology. Here in this study, the stress-induced failure mechanism caused by the constant program/erase cycling is demonstrated, tested and a data management solution for Eaton products, which are utilizing ASIC2, is provided

INVESTIGATION OF HIGH SCHOOL STUDENTS’ STEREOTYPED THOUGHTS ABOUT FOREIGN LANGUAGE AND ENGLISH SELF-EFFICACY PERCEPTIONS IN TERMS OF SOME VARIABLES

The aim of this study is to examine the relationship between stereotyped thoughts about foreign language and English self-efficacy perception of high school students in terms of various variables. 900 students from different high schools in Ankara, Turkey attended this study as a sample group. Data were collected through “Scale for Stereotyped Thoughts about Foreign Language” (Ünal, 2015) and “English Self-efficacy Perception” (Yanar, 2008). t-Test, one way ANOVA, Kruskal Wallis, Mann Whitney U, Pearson correlation, Regression analysis was used to analyze the data. This study was designed with comparative correlational survey design. There is statistically significant difference in their stereotyped thoughts about foreign language in terms of private/state high school, the aim of learning English variables. There are statistically significant differences in their foreign language self-efficacy perceptions in terms of private/state high school, weekly studying hours, and the aim of learning English variables. Pearson-r correlation revealed no significant relationship between the Stereotyped Thoughts toward foreign language and English Self-efficacy Perception of Students. Regression analysis showed that stereotyped thoughts can not predict English self-efficacy.  Article visualizations

Eski ramazan gecelerinde çalgılı kahveler

Taha Toros Arşivi, Dosya No: 134/B-Kahve. Not: Gazetenin "Ramazan Musahabeleri" köşesinde yayımlanmıştır.Unutma İstanbul projesi İstanbul Kalkınma Ajansı'nın 2016 yılı "Yenilikçi ve Yaratıcı İstanbul Mali Destek Programı" kapsamında desteklenmiştir. Proje No: TR10/16/YNY/010

The Phase Diagram of all Inorganic Materials

Understanding how the arrangement of atoms and their interactions determine material behavior has been the dominant paradigm in materials science. A complementary approach is studying the organizational structure of networks of materials, defined on the basis of interactions between materials themselves. In this work, we present the "phase diagram of all known inorganic materials", an extremely-dense complex network of nearly $2.1 \times 10^4$ stable inorganic materials (nodes) connected with $41 \times 10^6$ tie-lines (edges) defining their two-phase equilibria, as computed via high-throughput density functional theory. We show that the degree distribution of this network follows a lognormal form, with each material connected to on average 18% of the other materials in the network via tie-lines. Analyzing the structure and topology of this network has potential to uncover new materials knowledge inaccessible from the traditional bottom-up (atoms to materials) approaches. As an example, we derive a data-driven metric for the reactivity of a material as characterized by its connectedness in the network, and quantitatively identify the noblest materials in nature

Total quality management and its applications: Example of KalekimToplam kalite yönetimi ve uygulamaları: Kalekim örneği

The importance of Total Quality Management (TQM) can not be denied in increasing business efficiency and productivity. For this reason, companies should be able to apply this philosophy professionally in all business process. It has been stated that TQM is to be a philosophy which are reduces costs and defects, provides customer satisfaction, including workers in the decision-making processes and improves education in all business processes. However, some firms in Turkey can’t practice the TQM philosophy completely. Accordingly, it can be stated that many firms have some deficiencies to implement aims of this philosophy. The aim of this study is to explain the total quality management philosophy, its historical development process and some applications in the world and Turkey and to analyze TQM applications of Kalekim company. The results of this study show that Kalekim company implemented TQM applications successfully. Özetİşletmelerin etkinliklerinin ve verimliliklerinin artırılmasında Toplam Kalite Yönetimi (TKY)’ nin önemi yadsınamaz. Bu nedenle şirketler, bu felsefeyi tüm işletme süreçlerinde profesyonelce uygulayabilmelidir. TKY, tüm iş süreçlerinde, maliyetlerin ve hataların azaltıldığı, müşteri memnuniyetinin sağlandığı, işçilerin karar alma süreçlerine dahil edildiği, eğitimin artırıldığı bir felsefe olarak ifade edilmektedir. Ancak, Türkiye’deki bazı firmalar TKY felsefesini tam olarak uygulayamamaktadırlar. Dolayısıyla birçok firmanın bu felsefedeki amaçlarını gerçekleştirmede bazı eksiklileri olduğu söylenebilir. Bu çalışmanın amacı, TKY’nin felsefesini, tarihsel gelişimini, dünya ve Türkiye’deki bazı uygulamalarını belirtmek ve Kalekim firmasının TKY uygulamalarını analiz etmektir. Çalışma sonucunda, Kalekim firmasının TKY uygulamalarını başarı ile gerçekleştirdiği görülmüştür