An empirical investigation of performance overhead in cross-platform mobile development frameworks

The heterogeneity of the leading mobile platforms in terms of user interfaces, user experience, programming language, and ecosystem have made cross-platform development frameworks popular. These aid the creation of mobile applications – apps – that can be executed across the target platforms (typically Android and iOS) with minimal to no platform-specific code. Due to the cost- and time-saving possibilities introduced through adopting such a framework, researchers and practitioners alike have taken an interest in the underlying technologies. Examining the body of knowledge, we, nonetheless, frequently encounter discussions on the drawbacks of these frameworks, especially with regard to the performance of the apps they generate. Motivated by the ongoing discourse and a lack of empirical evidence, we scrutinised the essential piece of the cross-platform frameworks: the bridge enabling cross-platform code to communicate with the underlying operating system and device hardware APIs. The study we present in the article benchmarks and measures the performance of this bridge to reveal its associated overhead in Android apps. The development of the artifacts for this experiment was conducted using five cross-platform development frameworks to generate Android apps, in addition to a baseline native Android app implementation. Our results indicate that – for Android apps – the use of cross-platform frameworks for the development of mobile apps may lead to decreased performance compared to the native development approach. Nevertheless, certain cross-platform frameworks can perform equally well or even better than native on certain metrics which highlights the importance of well-defined technical requirements and specifications for deliberate selection of a cross-platform framework or overall development approach

Catalytic cleavage of HEAT and subsequent covalent binding of the tetralone moiety by the SARS-CoV-2 main protease

Here we present the crystal structure of SARS-CoV-2 main protease (Mpro) covalently bound to 2-methyl-1-tetralone. This complex was obtained by co-crystallization of Mpro with HEAT (2-(((4-hydroxyphenethyl)amino)methyl)-3,4-dihydronaphthalen-1(2H)-one) in the framework of a large X-ray crystallographic screening project of Mpro against a drug repurposing library, consisting of 5632 approved drugs or compounds in clinical phase trials. Further investigations showed that HEAT is cleaved by Mpro in an E1cB-like reaction mechanism into 2-methylene-1-tetralone and tyramine. The catalytic Cys145 subsequently binds covalently in a Michael addition to the methylene carbon atom of 2-methylene-1-tetralone. According to this postulated model HEAT is acting in a pro-drug-like fashion. It is metabolized by Mpro, followed by covalent binding of one metabolite to the active site. The structure of the covalent adduct elucidated in this study opens up a new path for developing non-peptidic inhibitors

Observer-based output feedback control of a PEM fuel cell system by high-order sliding mode technique

This paper deals with an high-order sliding-mode approach to the observer-based output feedback control of a PEM fuel cell system comprising a compressor, a supply manifold, the fuel-cell stack and the return manifold. The suggested scheme assumes the availability for measurements of readily accessible quantities such as the compressor angular velocity, the load current, and the supply and return manifold pressures. The control task is formulated in term of regulating the oxygen excess ratio (which is estimated by the observer) to a suitable set-point value by using, as adjustable input variable, the compressor supply voltage. The treatment is based on a nonlinear modeling of the PEM fuel cell system under study. Simulations results showing the feasibility and satisfactory performance of the proposed approach are provided

A rare case of donohue syndrome in a neonate: A case report

BACKGROUND AND OBJECTIVE: Donohue syndrome (DS) is an extremely rare and usually fatal inherited disease resulted from mutations in the INSR (Insulin Receptor) gene and delineated by severe insulin resistance with fasting hypoglycemia, postprandial hyperglycemia, and facial dysmorphism. Optimal treatment of these cases is unclear and most DS cases die during the first two years of life. Herein, we introduce a case of leprechaunism due to the rarity of this syndrome (one case in every four million birth) revealed by clinical and laboratory findings. CASE REPORT: We present a 4-day old boy with an abnormal facial appearance, low birth weight who was admitted to the Neonatal Intensive Care Unit (NICU) due to poor feeding and jaundice. The patient had coarse facies, hypertrichosis, abdominal distention, genitomegaly, and acanthosis nigricans. Laboratory examinations revealed fasting hypoglycemia, postprandial hyperglycemia, and hyperinsulinemia. The diagnosis of Donohue Syndrome was characterized by the combination of dysmorphic features and biochemical results. Supportive care such as normalizing blood glucose and continuous feeding was initiated. He was discharged with good condition several days later but was admitted again at 6 months of age due to sepsis and then died. CONCLUSION: According to the present case report, close monitoring of blood glucose as well as caring to prevent infection and sepsis is recommended. © 2021, Babol University of Medical Sciences. All rights reserved

Surface characterization of nitrogen-doped Nb (100) large-grain superconducting RF cavity material

(100) Oriented niobium (Nb) crystals annealed in the vacuum conditions close to that used in mass production of 1.3 GHz superconducting radio frequency cavities for linear accelerators and treated in nitrogen at a partial pressure of 0.04 mbar at temperatures of 800 and 900 °C have been studied. The surfaces of the nitrogen-treated samples were investigated by means of various surface-sensitive techniques, including grazing-incidence X-ray diffraction, X-ray photoemission spectroscopy, and scanning electron microscopy with energy-dispersive X-ray spectroscopy in planar view and on cross-sections prepared by a focused ion beam. The appearance of a dense layer of epitaxial rectangular precipitates has been observed for the Niobium nitrided at 900 °C. Increased nitrogen concentration in the near-surface region was detected by glow-discharge optical-emission spectroscopy, focused ion-beam cross-sectional images and X-ray photoelectron spectroscopy. Crystalline phases of NbO and β-Nb2N were identified by X-ray diffraction. This information was confirmed by X-ray photoelectron measurements, which in addition revealed the presence of Nb2O5, NbON, NbN, and NbN x O y components on the surface. These results establish the near-surface Nb phase composition after high-temperature nitrogen treatment, which is important for obtaining a better understanding of the improved RF cavity performance

Operando reaction cell for high energy surface sensitive x-ray diffraction and reflectometry

A proof of concept is shown for the design of a high pressure heterogeneous catalysis reaction cell suitable for surface sensitive x-ray diffraction and x-ray reflectometry over planar samples using high energy synchrotron radiation in combination with mass spectrometry. This design enables measurements in a pressure range from several tens to hundreds of bars for surface investigations under realistic industrial conditions in heterogeneous catalysis or gaseous corrosion studies

Atomic structure and stability of magnetite Fe3O4(001)Fe_{3}O_{4}(001): An X-ray view

The structure of the Fe$_{3}$O$_{4}$(001) surface was studied using surface X-ray diffraction in both ultra-high vacuum, and higher-pressure environments relevant to water–gas shift catalysis. The experimental X-ray structure factors from the $\sqrt{2}\times\sqrt{2}$ R 45∘ reconstructed surface are found to be in excellent agreement with the recently proposed subsurface cation vacancy (SCV) model for this surface (Science 346 (2014), 1215). Further refinement of the structure results in small displacements of the iron atoms in the first three double layers compared to structural parameters deduced from LEED I–V experiments and DFT calculations. An alternative, previously proposed structure, based on a distorted bulk truncation (DBT), is conclusively ruled out. The lifting of the $\sqrt{2}\times\sqrt{2}$ R 45∘ reconstruction upon exposure to water vapor in the mbar pressure regime was studied at different temperatures under flow conditions, and a roughening of the surface was observed. Addition of CO flow did not further change the roughness perpendicular to the surface but decreased the lateral correlations

Single orientation graphene synthesized on iridium thin films grown by molecular beam epitaxy

Heteroepitaxial iridium thin films were deposited on (0001) sapphire substrates by means of molecular beam epitaxy, and subsequently, one monolayer of graphene was synthesized by chemical vapor deposition. The influence of the growth parameters on the quality of the Ir films, as well as of graphene, was investigated system atically by means of low energy electron diffraction, x-ray reflectivity, x-ray diffraction, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Our study reveals (111) oriented iridium films with high crystalline quality and extremely low surface roughness, on which the formation of large-area epitaxial graphene is achieved. The presence of defects, like dislocations, twins, and 30$^\circ$ rotated domains in the iridium films is also discussed. The coverage of graphene was found to be influenced by the presence of 30$^\circ$ rotated domains in the Ir films. Low iridium deposition rates suppress these rotated domains and an almost complete coverageof graphene was obtained. This synthesis route yields inexpensive, air-stable, and large-area graphene with a well-defined orientation, making it accessible to a wider community of researchers for numerous experiments or applications, including those which use destructive analysis techniques or irreversible processes. Moreover, this approach can be used to tune the structural quality of graphene, allowing a systematic study of the influence of defects in various processes like intercalation below graphene