Equilibrium at the edge and atomistic mechanisms of graphene growth

The morphology of graphene is crucial for its applications, yet an adequate theory of its growth is lacking: It is either simplified to a phenomenological-continuum level or is overly detailed in atomistic simulations, which are often intractable. Here we put forward a comprehensive picture dubbed nanoreactor, which draws from ideas of step-flow crystal growth augmented by detailed first-principles calculations. As the carbon atoms migrate fromthe feedstock to catalyst to final graphene lattice, they go through a sequence of states whose energy levels can be computed and arranged into a step-by-step map. Analysis begins with the structure and energies of arbitrary edges to yield equilibrium island shapes. Then, it elucidates how the atoms dock at the edges and how they avoid forming defects. The sequence of atomic row assembly determines the kinetic anisotropy of growth, and consequently, graphene island morphology, explaining a number of experimental facts and suggesting how the growth product can further be improved. Finally, this analysis adds a useful perspective on the synthesis of carbon nanotubes and its essential distinction from graphene

Breaking of symmetry in graphene growth on metal substrates

In graphene growth, island symmetry can become lower than the intrinsic symmetries of both graphene and the substrate. First-principles calculations and Monte Carlo modeling explain the shapes observed in our experiments and earlier studies for various metal surface symmetries. For equilibrium shape, edge energy variations ??E manifest in distorted hexagons with different ground-state edge structures. In growth or nucleation, energy variation enters exponentially as ???e??E/kBT, strongly amplifying the symmetry breaking, up to completely changing the shapes to triangular, ribbonlike, or rhombic. © 2015 American Physical Societyopen1

Marketing communication strategies of colleges and universities based on spatial and temporal distribution of students

The development of marketing strategies based on temporal and spatial student’s distribution is extremely important in order to win a niche in the market of educational services. The object of the study is information about the place of origin of the Henan Institute of Science and Technology students in 2016 and 2020. The data used are provided by the Office of Academic Affairs of Henan Institute of Science and Technology, which selects identity data of students admitted and registered at the university in 2016 and 2020. The temporal and spatial distribution and spatial aggregation characteristics of the student enrolments are analyzed, as well as factors affecting the quality of the student flows, such as geographic location, total number of students per year, and publicity. The paper uses spatial data analysis (ESDA), which determines the spatial weight between districts. Global Moran’s I index was used for spatial analysis. The analysis carried out on the example of Henan province showed that the number of graduates in each city in a given year directly affects the number of university entrants (in 2020, the largest number of school graduates was recorded in the cities of Zhoukou and Nanyang, which had the highest number of university entrants). The spatial arrangement of colleges and universities is identified as the main factor influencing the recruitment of students of each educational institution. The choice of colleges and universities by applicants and their parents in China is also determined by proximity to large cities, convenient transportation, and employment opportunities. It has been established that advertising educational services of universities is also an additional factor in their popularization and attraction of students. The important achievements and characteristics of the school should be highly summarized to ensure that all the information on the school brand is spread in the whole domain in a comprehensive manner. Different media should be selected for different students from different places. Attention should be paid to the use of new media such as WeChat, Micro-blog, Tiktok etc. Also, a significant role should be given to interpersonal communication and mobilization of the enthusiasm of graduates to increase the popularity of a particular educational institution. Colleges and universities should reflect on themselves, correct in time, and actively establish a complete, effective, and dynamic evaluation mechanism for marketing, to improve marketing strategies, including through surveys of graduates, students, parents and other stakeholders of higher education

Problems of diagnostic management of congenital myotonia: to execute or to pardon

Congenital myotonia is a monogenetic disease, hereditary neuromuscular chanalopathy that affects skeletal muscles. Two types of myotonia congenita exist; autosomal dominant myotonia congenita also called Thomsen disease (OMIM160800), and recessive generalized myotonia (RGM) or Becker myotonia (OMIM 255700). Because several CLCN1 mutations can cause either Becker myotonia or Thomsen myotonia, doctors usually rely on characteristic signs and symptoms to distinguish the two forms of myotonia congenita. However, diagnostic errors are very common at the level of primary health care. The authors present a clinical case of late diagnosis of congenital myotonia (variant pseudo-Becker) in 42 years old man. Execution or to pardon the doctor who prescribed molecular diagnostic testing, which is not included in the approved standards?Врожденная миотония - моногенное заболевание, наследственная каналопатия, при которой поражаются скелетные мышцы. Выделяют два типа врожденной миотонии: аутосомно-доминантную врожденную миотонию, также называемую миотонией Томсена (0М1М 160800), и аутосомно-рецессивную генерализованную миотонию (РГМ) или миотонию Беккера (0MIM 255700). Поскольку несколько мутаций гена хлорного канала CLCN1 могут вызвать либо миотонию Томсена, либо миотонию Беккера, врачи обычно полагаются на характерные признаки и симптомы, чтобы различать эти две формы врожденной миотонии. Однако диагностические ошибки очень часты на уровне первичного звена здравоохранения. Одной из ведущих проблем диагностического менеджмента врожденной миотонии является низкая доступность молекулярно-генетического исследования для населения нашей страны, потому что этот вид диагностики не входит в программу государственных гарантий до настоящего времени. Авторами представлен клинический случай поздней диагностики врожденной миотонии (вариант псевдо-Беккера) у 42-летнего мужчины. Казнить или помиловать врача, который назначил молекулярно-диагностическое обследование, не входящее в утвержденные стандарты

An improvement of the Berry--Esseen inequality with applications to Poisson and mixed Poisson random sums

By a modification of the method that was applied in (Korolev and Shevtsova, 2009), here the inequalities $$\rho(F_n,\Phi)\le\frac{0.335789(\beta^3+0.425)}{\sqrt{n}}$$ and $$\rho(F_n,\Phi)\le \frac{0.3051(\beta^3+1)}{\sqrt{n}}$$ are proved for the uniform distance $\rho(F_n,\Phi)$ between the standard normal distribution function $\Phi$ and the distribution function $F_n$ of the normalized sum of an arbitrary number $n\ge1$ of independent identically distributed random variables with zero mean, unit variance and finite third absolute moment $\beta^3$. The first of these inequalities sharpens the best known version of the classical Berry--Esseen inequality since $0.335789(\beta^3+0.425)\le0.335789(1+0.425)\beta^3<0.4785\beta^3$ by virtue of the condition $\beta^3\ge1$, and 0.4785 is the best known upper estimate of the absolute constant in the classical Berry--Esseen inequality. The second inequality is applied to lowering the upper estimate of the absolute constant in the analog of the Berry--Esseen inequality for Poisson random sums to 0.3051 which is strictly less than the least possible value of the absolute constant in the classical Berry--Esseen inequality. As a corollary, the estimates of the rate of convergence in limit theorems for compound mixed Poisson distributions are refined.Comment: 33 page