bluuebunny/crossref_metadata_2025 huggingface dataset:
Hydrodynamic Modeling of Sailing Yachts
Authors: Harries Stefan , Abt Claus , Hochkirch Hochkirch
Published: May 2021

In modem yacht design geometric modeling is regarded to be directly related to the hydrodynamic performance of the shape of the hull and its appending elements -usually the keel, often with winglets, and the rudder. While the traditional way of shape design - i.e., draw­ing, model building, tank testing, modifying . - is both time consuming and expensive, a complementing ap­proach shall be discussed within this paper. The ap­proach is called hydrodynamic modeling since it tightly combines the hydrodynamic analysis and the geomet­ric modeling in the design process. It is based on ad­vanced Computational Fluid Dynamics (CFD) methods for flow field analysis and unique parametric modeling techniques for shape generation.

The geometry of a yacht is entirely described via im­portant form parameters as discussed in detail by the authors at the 1999 CSYS. The canoe body of the yacht is modeled from a small set of longitudinal curves which provide all parameters needed for sectional design. The longitudinal curves themselves being created via form parameters, a fully parametric description of the hull is achieved which allows to create and modify the geom­etry in a highly sophisticated manner. The fairness of the shapes is an intrinsic part of the form generation procedure. Apart from the canoe body the keel repre­sents the most pronounced hydrodynamic design ele­ment, dominating lift and righting moment of a yacht but also causing a non-negligible resistance component called induced drag. Keel, bulb and winglets are also specified in terms of form parameters.

An application of hydrodynamic modeling is given for an IACC-yacht. Formal optimization can be suc­cessfully employed to identify improved and, eventu­ally, optimal configurations. A reasonably small set of parameters (free variables) was selected and systemati­cally varied making use of a fully automatic optimiza­tion scheme. Two optimization examples are presented in order to demonstrate the potential of the approach: (a) the optimization of a keel-bulb-winglet configuration so as to find a minimum drag solution for a given side force and (b) the optimization of the bare hull with respect to wave resistance.

The examples can be regarded as representative for both racing and touring yachts with draft restrictions and illustrate the methodology of hydrodynamic modeling.
Schooner Brilliant Sail Coefficients and Speed Polars
Authors: Grant Howard , Stubner Walter , Alwang Walter , Henry Charles , Baird John , Spens Paul
Published: May 2021

The sail coefficients for a schooner rig, as a function of wind angle and heel angle, are presented, based on an experimental program, for historic vessel research, at Mystic Seaport, using the 61'6" schooner Brilliant. The coefficients were determined by full-scale sailing tests and 9- scale model tow-tank tests.

Sail coefficients CR and Cttare defined as the drive force and horizontal side force , due to the sails, rigging, and hull above the waterline, per unit of sail area, per unit of wind pressure. These coefficients can be used to study performance of historic schooner­rigged vessels, predict performance of new designs, and compare performance of schooners and sloops. Sail coefficients for sloops have long been available.

A velocity prediction program for the schooner was also developed. The predicted and actual ship speeds agree, with standard deviation of0.028 in the ratio.

Upwind sail coefficients for the schooner are found to be lower than for historic sloops, and display the expected droop with heel. The schooner velocity made good upwind is largest with the sail plan of four lowers plus fisherman staysail. The schooner and sloop both point higher as wind increases. The sloop outpoints the schooner at all wind speeds, by about 10°.

On a beam reach or broad reach, schooner speed is largest with the sail plan of big jib, golliwobbler, and mainsail. This sail plan also produces the largest downwind velocity made good. The polars suggest that the schooner has the advantage over the sloop on a beam reach.
Application of Fast Synchrotron X-ray Imaging in Velocimetry of Cavitating Flows
Authors: Ge Mingming , Zhang Guangjian , Nematikourabbasloo Navid , Fezzaa Kamel , Coutier-Delgosha Olivier
Published: May 2021

Hydrodynamic cavitation is a complex two-phase flow phenomenon involving mass and heat transfer between liquid and vapor. It occurs in many widely-used hydraulic machines, such as pumps and marine propellers, and often leads to undesired effects like material erosion, noise, and vibration. To control these detrimental effects, the visualization of two-phase flow morphology inside the opaque cavity is a crucial point to improve the physical and numerical models of cavitation. The major challenge in experimental measurements of cavitating flow fields is the fact that multiple scattering and a direct reflection of visible light from phase boundaries make the flow optically opaque. In recent years, unlike traditional local measurements using various probes, the development of the third-generation synchrotron radiation sources promotes the application of Xray phase-contrast imaging, which enables clear visualization of boundaries between phases with different refractive indices. In this study, the partial cavity is formed in a convergent-divergent (Venturi) channel with a small contraction ratio where the relatively stable cavitation regime can be sustained in a wide range of cavitation numbers. The experiment performed at Advanced Photon Source (APS) of Argonne uses the short high-flux X-ray pulses emitted from synchrotron sources to capture fast dynamic events and minimize motion blur. The internal two-phase structures and bubble development dynamics inside the quasi-stable sheet cavitation can be identified. Aside from the detailed illustration of two-phase morphology, X-ray phase-contrast images were also used to perform velocimetry by tracking either seeded particles or phase interfaces inside the opaque regions. Through appropriate postprocessing to the recorded X-ray images of cavitation, the time resolved velocity and void fraction fields are obtained simultaneously. These unprecedented experimental data will be further explored in understanding fluid mechanics underneath the cavity, estimating slip velocity between fluid-vapor interactions, and reconstructing pressure fields for compressible flows.
Los MOOC en la línea del tiempo: una biografía investigativa de una tendencia educativa
Authors: Chiappe Andres , Amaral Monique
Published: May 2021

Los cursos online masivos y abiertos (MOOC) se han convertido en un fenómeno educativo emergente con un enorme potencial de transformación y democratización educativa. Luego de casi una década de su primer lanzamiento, gran cantidad de investigación se ha realizado para intentar comprender sus alcances y limitaciones como instrumento de aprendizaje flexible y personalizado. Con el propósito de aumentar tal comprensión, se ha llevado a cabo una revisión sistemática de literatura sobre estudios publicados entre 2009 y 2019 acerca de los MOOC. Se aplicó un método de 6 pasos para revisar 486 estudios, a partir de procesos de filtrado, abstracting, lectura en profundidad y extracción e interpretación de datos. Los resultados muestran una gran cantidad y diversidad de focos de investigación sobre los MOOC, algunos en auge, otros en declive y otros de naturaleza efímera. Se resaltan entre ellos las Prácticas Educativas Abiertas, el diseño de los MOOC, el engagement, la deserción y el conectivismo. Los focos de investigación representan las principales preocupaciones de educadores e investigadores sobre lo que pareciera ser el advenimiento de un nuevo orden educativo que soportaría el aprendizaje a lo largo de la vida y los entornos de aprendizaje enmarcados en la sociedad 4.0.

Massive and open online courses (MOOC) have become an emerging educational phenomenon with enormous potential for educational transformation and democratization. After almost a decade of its first launch, a great deal of research has been carried out to try to understand its scope and limitations as a flexible and personalized learning instrument. In order to increase such understanding, a systematic review of literature on studies published between 2009 and 2019 about MOOCs has been carried out.A 6-step method was applied to review 486 studies, based on filtering, abstracting, in-depth reading and data extraction and interpretation processes.The results show a large number and diversity of research focuses on MOOCs, some booming, others in decline and others of ephemeral nature. Among them are the Open Educational Practices, the design of MOOCs, the generation of engagement, dropout and connectivism.The research focuses represent the main concerns of educators and researchers regarding what appears to be the advent of a new educational order, which currently supports lifelong learning and future learning environments framed in society 4.0.
Content analysis of research papers on flipped learning
Authors: Uzunboylu Huseyin , Prevalle Ethemi Blerta , Hamidi Mentor
Published: May 2021

Abstracto

El propósito de este estudio es describir el estado actual de la publicación de investigaciones y las tendencias en el aprendizaje invertido, que se encuentran en "Web of Science" durante el período 2014-2018. Hay 262 artículos investigados, publicados e indexados en "Web of Science" con la palabra clave: "aprendizaje invertido" y "aula invertida". Los resultados del estudio se analizan según la revista de publicación según estos criterios: autor, países, agencias de financiación, tipos de documentos, idiomas, organización, años de publicación y título de la fuente. El aprendizaje invertido cambia la clase tradicional dando la vuelta al aula en el sentido de escuchar las videoconferencias en casa y realizar actividades dinámicas en grupo en el aula. Esto involucra a los estudiantes en el aprendizaje activo, el pensamiento crítico y mejora las habilidades interpersonales.Se recomienda a los autores explorar la posibilidad de utilizar este método, experimentar y publicar los hallazgos que permitan crear mejores prácticas y un marco unificado para instructores líderes que deseen adoptar esta metodología de enseñanza.

Palabras clave: aprendizaje invertido, aula invertida, análisis de contenido,

 

The purpose of this study is to describe the current state of research publication and trends in flipped learning, found on ‘Web of Science’ during the period 2014–2018. There are 262 papers investigated, published and indexed on ‘Web of Science’ with the keyword: “flipped learning” and “flipped classroom”. The results of the study are analysed according to the journal of publication by these criteria: author, countries, funding agencies, document types, languages, organisation, publication years and source title. Flipped learning changes the traditional lecturing by flipping the classroom in the sense of listening to the video lectures at home and doing dynamic, group-based activities in the classroom. This engages the students in active learning, critical thinking, and meliorates interpersonal skills.It is recommended to authors to explore the possibility of utilising this method, experimenting and publish the findings which allows to create best practices and a unified framework for leading instructors who want to adopt this teaching methodology.

Keywords: Flipped learning, flipped classroom, content analysis,
ADSORPTION OF ETHOXYLATED ISONONYLPHENOLS ON CARBON NANOTUBES FROM AQUEOUS SOLUTIONS
Authors: Gataullin Azat R. , Bogdanova Svetlana A. , Galyametdinov Yuriy G.
Published: May 2021

One of the approaches to solving the problem of carbon nanotubes dispersions obtaining is the use of nonionic surfactants in the processes of ultrasonication of carbon nanostructures in aqueous solutions. The effect of nonionic surfactants on dispersing and stabilizing is determined by the adsorption interaction of surfactant molecules with a graphene surface, the study of which can reveal important patterns of stable carbon nanotubes dispersions obtaining during ultrasonic treatment in liquid media. The aim of this work was to study the adsorption of ethoxylated isononylphenols with a variable average degree of ethoxylation on single-walled and multi-walled carbon nanotubes from aqueous solutions. The value of adsorption of nonionic surfactants on carbon nanotubes was calculated on the basis of changes in the equilibrium concentration of ethoxylated isononylphenols in the solution at presence of carbon nanotubes. The equilibrium concentration of nonionic surfactants was determined by absorption spectroscopy. It was found that the shape of adsorption isotherms of the ethoxylated isononylphenols on carbon nanotubes from aqueous solutions before ultrasonic treatment corresponds to the Langmuir adsorption isotherm L2. The values of maximum adsorption of ethoxylated isononylphenols were shown to decrease with an increase in the average degree of ethoxylation. Obviously, this is due to conformational changes in the polar chain, showed in the sizes of ethoxylated isononylphenols micelles, in the structure of the adsorption layer. It has been established that the hydrophobic interaction of the surfactants hydrocarbon radical with a graphene surface is the main mechanism for the adsorption of ethoxylated isononylphenols on carbon nanotubes. The dispersions of carbon nanotubes in micellar solutions of nonionic surfactants were obtained and studied. It was shown that ultrasonic treatment leads to a change in the mechanism of nonionic surfactants adsorption on carbon nanotubes.
HYDROPHOBIZATION OF SILICA PARTICLES WITH VARIOUS CATIONIC SURFACTANTS
Authors: Nushtaeva Alla V. , Vilkova Natalia G.
Published: May 2021

Silica particles with a radius of 3-7 nm (Ludox and Aerosil) and 270 nm (synthesized by the Stöber method), modified with cetyltrimethylammonium bromide (CTAB) and hexylamine, were used to stabilize emulsions. The hysteresis angles θ of the particle selective wetting were measured by the sessile droplet method on the vertical surface or by the pulling a ball method at using a glass substrate modified by contact coagulation of silica. The contact angle at the boundary between the aqueous phase and the saturated hydrocarbon (octane, decane) reached the values θrec = 53 ± 2 ° and θadv = 116 ± 4 ° (the aqueous phase receding and advancing angle, respectively) with an increase in the initial concentration of long-chain CTAB to (1.4–9.5)·10–2 mmol/g of silica. With a further increase in CTAB concentration, a second reoriented layer was formed, which lowered the contact angle. Accordingly, using CTAB, only oil-in-water emulsions were obtained with the oil phase volume fraction Øoil = 0.5. The amount of short-chain hexylamine required to start stabilizing the emulsions turned out to be 2-3 orders of magnitude higher than the amount of CTAB. At using hexylamine, it was possible to increase the contact angle up to the values θrec ≈ θadv = 163 ± 12 ° at a concentration of 7-21 mmol/g. This is due to the fact that hexylamine is not characterized by formation of micelle or reoriented layers. Apparently, the adsorption of hexylamine is possible not only on dissociated silanol groups Si–OH, but also on siloxane groups Si–O–Si≡, which makes it possible to make the silica surface superhydrophobic. The measured contact angles were correlated with the region of stable oil-in-water and water-in-oil emulsions.
COMPARATIVE IN VITRO ANALYSIS OF CYTOTOXICITY OF BODIPY-LUMINOPHERS AS POTENTIAL FLUORESCENT SENSORS FOR BIOLOGICAL SYSTEMS
Authors: Aleksakhina Elena L. , Pakhrova Olga A. , Tomilova Irina K. , Merkushev Dmitry A. , Molchanov Evgeny E. , Usoltsev Sergei D. , Vodyanova Olga S. , Marfin Yuriy S.
Published: May 2021

Boron dipyrrin (BODIPY) based luminophores are of considerable interest as promising components of optically active molecular devices for sensing, visualization, and theranostics of biological systems. However, the toxic effect of boron dipyrrin based luminophores of various structure have not been systematically studied until now. In this regard, the work shows the spectral characteristics of the main groups of BODIPY luminophores, which differ in the nature of substituents in the structure of the dipyrrine ligand, as well as in the length of the aromatic system, which can be used to solve practical problems of molecular sensorics of biosystems. The cytotoxicity of the compounds was evaluated. In the study within the framework of an integrated approach, two groups of methods were used to study the effect of the compounds under study at the cellular level: assessment of the cytotoxic effect on the morphological characteristics of blood cells using phase contrast microscopy with detection of altered cells and the intensity of free radical processes of cell membrane degradation. The results of the study of changes in the antioxidant system of blood samples during incubation with all dyes did not reveal significant differences. do not show cytotoxic effect. It was found that BODIPY has a potential membrane-protective effect, which was shown in this study for the first time.
SYNTHESIS AND PROPERTIES OF 2-HYDROXY-5[1(3)-METHYLCYCLOALKYL]-BENZYLAMINOETHYLNONYLIMIDAZOLINES
Authors: Rasulov Chingiz K. , Aghamaliyev Zaur Z. , Nagiyeva Mekhriban V. , Gasanova Gulshan D. , Gasimova Fatma I.
Published: May 2021

The paper deals with the results of cycloalkylation of phenol with 1-methylcyclopentene, 1(3)-methylcyclohexene in the presence of KU-23 catalyst and influence of various parameters on the yield of the target product. The reaction temperature was varied from 80 to 140 °C, the reaction time - from 2 to 8 h, molar ratio of phenol to cyclene – from 1:2 to 2:1 mol/mol, the catalyst amount – from 5 to 15%. Maximum yield of para-[1(3)-methylcycloalkyl] phenols is obtained under the following conditions: temperature – 110-120 °C, duration – 5-6 h, molar ratio of phenol to 1(3)-methylcycloalkene – 1:1 mol/mol and the catalyst amount is 10% based on taken phenol. Simultaneously, the yield of the target products – para-[1(3)-methylcycloalkyl] phenols is 68.6-73.5% per taken phenol, the selectivity is 91.8-94.3% on the target product. As a result of the chromatographic studies of the products of phenol cycloalkylation with 1(3)-methylcycloalkenes in the presence of KU-23 catalyst it becames clear that the alkylate mainly contains paracycloalkyl-substituted phenols (89.6-94.1%). After rectification of the alkylate at low pressure (10 mm Hg), the target products were obtained with a purity of 97.6-98.2% and their physico-chemical properties were determined. The resulting para-[1(3)-methylcycloalkyl] phenols were aminomethylated by formaldehyde and aminoethylnonylimidazoline at the ratio of 1:2:2. As a result, Mannich bases were obtained with yield of 68.3-76.7% from theory. The synthesized methylcycloalkylbenzylaminoethylnonylimidazolines were tested as antioxidants of M-8 engine oil. The oxidation resistance of the oil has been investigated without the addition and with the addition of ИХП-21 antioxidants, known benzylphenylamines and the compounds of the invention. Addition of the obtained compounds to the base oil leads to enhancement of its antioxidant properties, at application of which viscosity increase is 14.07-15.28%, and precipitate - 0.45-0.57%.
STUDY AND MODELING 4,4'-DIAMINODIPHENYLMETHANE SYNTHESIS
Authors: Menshutina Natalia V. , Lebedev Igor V. , Lebedev Evgeniy A. , Dashkin Ratmir R. , Shishanov Mikhail V. , Burdeyniy Maxim L.
Published: May 2021

The presented work is devoted to reactions of obtaining 4,4´-diaminodiphenylmethane in the presence of a catalyst. The work describes the importance of studying 4,4´-diaminodiphenylmethane obtaining process and possibility of cellular automata approach in modelling chemical reactions. Cellular automata model which allows to predict the kinetic curves of the studied 4,4´-diaminodiphenylmethane-obtaining reaction. Model reflects two processes that are observed in the system under study - the movement of reagents under the stirring and the reaction in the presence of a catalyst. The suggested model does not use complex calculations for operation and can be implemented using high-performance parallel computing, which will speed up calculations and reduce the requirements for computing resources. The developed model was used to carry out computational experiments under various conditions. Since the model contains a number of empirical parameters, first computational experiments were carried out, which made it possible to establish the relationship between the model parameters and real values. Then, computational experiments were carried out to predict the kinetic curves of the studied reactions and were compared with the corresponding experimental data. The suggested model is suitable for predicting 4,4´-diaminodiphenylmethane-obtaining reaction kinetics. Also, model can be the part of complex multiscale modeling from the molecule level to the level of the entire apparatus.
ADDITIVES FOR HEAVY CONCRETE BASED ON INDUSTRIAL WASTE FROM CHEMICAL INDUSTRIES
Authors: Polyakov Igor V. , Barannikov Mikhail V. , Stepanova Ekaterina A.
Published: May 2021

The effect of a complex additive containing superplasticizer C-3 on the properties of heavy concrete has been investigated. The efficiency of the plasticizing action of the specified additive at the stage of preparation of the concrete mixture and subsequent molding of concrete products has been revealed. It is proved that at the stage of concrete hardening, the investigated additive promotes to the formation of a more homogeneous colloidal-crystalline structure and the formation of dense crystalline hydrate complexes of cement stone by the time of completion of concrete hardening. The objects of investigation were samples of grade B22.5 concrete without additives; containing a monoadditive - superplasticizer S-3; containing the complex additive. When designing the composition of additives for heavy concrete, we proceeded from the fundamental provisions of construction science that the complexity of the action of additives lies in the optimal combination of two main opposite processes in time and volume of the concrete matrix. The use of the caprolactam oligomer synthesized in the course of this investigation makes it possible to solve the problem of involving concentrated wastes of caprolactam production in the production turnover. The obtained caprolactam oligomers can be used in construction as plasticizers of concrete mixtures, as inhibitors of corrosion of steel reinforcement in the production of reinforced concrete products. Water-soluble oligomers of caprolactam, which reduce the time of dissolution of the superplasticizer C-3 and the dispersion of low-temperature catalyst in the volume of the concrete mixture being mixed, were synthesized. It was found that in the presence of the oligomer caprolactam in an amount of 10 to 20% of the mass. the dissolution rate of S-3 superplasticizer in water at a temperature of 20-21 °C increases by 2.0-2.2 times. This contributes to a better mixing of the components of the concrete mixture, primarily to improve the dispersion of the complex additive in the volume of the concrete mixture. The caprolactam oligomer used in this research work is an effective water-soluble wetting agent for the surface of particles of cement, sand, and crushed stone, which is very important for activating hydration and sorption processes during mixing of a concrete mixture. The increased wetting properties of the caprolactam oligomer are characterized by a wetting angle of 19.6 °.
RESEARCH OF POSSIBILITY OF PROCESSING PETROLEUM COKE WITH INCREASED VOLATILE SUBSTANCES INTO ACTIVATED CARBONS
Authors: Farberova Еlena A. , Maximov Andrey S. , Tingaeva Elena A. , Shirkunov Anton S. , Ryabov Valeriy G. , Strelkov Vasiliy A.
Published: May 2021

In present work, study to obtain granulated active carbon based on industrial petroleum coke of the CEL grade (coke with an increased content of volatile substances) produced in delayed coking unit have been conducted. The production of activated carbons was carried out by preliminary carbonization of coke at a temperature of 500-800 °C, followed by activation in a water vapor atmosphere at a temperature of 850-900 °C. In addition, tests were carried out on the effect of impregnation of the initial coke with aqueous solutions of chemical activators (sodium hydroxide, potassium carbonate, phosphoric acid) on the efficiency of heat treatment and characteristics of the porous structure of the resulting sorbent. The use of sodium hydroxide as an activating agent increases the reactivity of the sample, but the microporous structure does not develop. Using potassium carbonate as the activating solution and increasing the carbonization temperature to 800 °C causes an increase in the degree of burning from 28 to 44 %. However, activation of the resulting carbonizates with superheated steam leads to a 97-98 % burn-out of the samples due to a sharp increase in reactivity. It was shown that activated carbon obtained on the base of petroleum coke with an increased content of volatile substances by preliminary impregnation with an aqueous solution of phosphoric acid (concentration 17 wt.%), filtration and drying, followed by carbonization at a temperature of 800 °C in an inert atmosphere and activation in water vapor medium at a temperature of 850-900 °С has a sufficiently high specific surface of micropores (up to 430 m2/g) and other characteristics of the porous structure. Thus, the proposed method can serve as one of the ways to expand the qualified use of petroleum coke.
SYNTHESIS OF 3,3´-(1,4-PHENYLENE)BIS(1-(4-R-PHENYL)-5-PHENYL-5,6-DIHYDRO-1,2,4,5-TETRAZINIUM) PERCHLORATES
Authors: Kostryukov Sergey G. , Kozlov Artur Sh. , Krasnov Dmitry A. , Tezikova Veronika S. , Masterova Yulia Yu. , Klimaeva Lyudmila A.
Published: May 2021

A series of 3,3'-(1,4-phenylene)bis(1-4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium) perchlorates containing hydrogen, methyl, bromio, methoxy, acetyl and nitro groups (R = H, Me, Br, OMe, COMe, NO2) as substituents were obtained as a result of a three-stage synthesis from terephthalic aldehyde. The synthesis of tetrazinium salts was carried out by reaction of the corresponding formazans with formalin in the presence of perchloric acid in dioxane. Formazans were obtained by reaction of terephthalic aldehyde phenylhydrazone with arenediazonium tosylates in a mixture of DMF and pyridine. The usage of arenediazonium tosylates made it possible to extremely simplify the segregation and purification of formazans. The phenylhydrazone was synthesized according to the standard procedure from terephthalic aldehyde and phenylhydrazine/hydrochloric acid in aqueous dioxane. The formazans and tetrazinium perchlorates were isolated in individual state and characterized by elemental analysis, IR, UV, 1H and 13C NMR spectroscopy data. The process of electrochemical reduction of tetrazinium perchlorates was studied using the method of cyclic voltammetry (CV). Thus, the CV curves of all salts in the cathode region contain two one-electron reduction peaks, which are related to the sequential formation of a radical cation and a biradical. It was found that electron-donating substituents (R = Me, OMe) in the aromatic ring at position 1 facilitate the reduction of tetrazinium cation, while electron-withdrawing substituents (R = COMe, NO2) hinder this process. On this basis, it was suggested that the corresponding bis-verdazyl radicals should be easily formed in the presence of electron-donating substituents in the aromatic ring at position 1. Thus, 3,3´-(1,4-phenylene)bis(1-(4-R-phenyl)-5-phenyl-5,6-dihydro-1,2,4,5-tetrazinium-1) perchlorates are perspective precursors of symmetric biradical systems based on verdazyl radicals.
DETERMINATION OF PIROCARBON MATRIX CHARACTERISTICS IN CARBON/CARBON COMPOSITES
Authors: Papkova Maria V. , Tashchilov Sergei V. , Magnitsky Ilya V. , Dvoretsky Alexander E.
Published: May 2021

One of the methods of carbon/carbon composites (C/C composites) production is the deposition of a pyrocarbon (pyC) matrix in a porous preform. The investigation of the pyC matrix characteristics is based on the optical anisotropy with determination of the extinction angle Ae and X-ray diffraction determination of the interplanar spacing d002, crystallite size in the direction of stacking of graphite layers Lc and average size of graphite planes parallel layer in crystallites La. In this study, three previously produced by the thermal gradient method with different parameters specimens of C/C composites were investigated by optical microscopy and X-ray diffraction methods. The studied specimens have a different type of a texture and different structural characteristics of the pyC matrix. Extinction angle Ae for specimen 1, specimen 2 and 3 was 5°, 19° and 41°, respectively. The range of the extinction angle for the pyC matrix is wider than that presented in literature. And according to the classification of pyC the matrix of specimen 1, specimen 2 and 3 is dark laminar pyC, rough laminar pyC and highly textured pyC. For specimen 2 the largest d002 equal to 0.3476 nm was observed. The lowest degree of three-dimensional ordering relative other specimens was for the specimen 2 with rough laminar pyC matrix. The highest degree of three-dimensional ordering was for the specimen 3 with highly textured pyC matrix. However, there is no direct relationship between the textural and structural characteristics of the pyC matrix. Therefore, the study of the pyC matrix should be based on optical and X-ray diffraction methods.
ПАРАМЕТРЫ ГАЗОВОЙ ФАЗЫ И РЕЖИМЫ РЕАКТИВНО-ИОННОГО ТРАВЛЕНИЯ Si И SiO2 В БИНАРНЫХ СМЕСЯХ Ar + CF4/C4F8
Authors: Efremov Alexander M. , Betelin Vladimir B. , Mednikov Konstantin A. , Kwon Kwang-Ho
Published: May 2021

The comparative study of plasma electro-physical parameters, steady-state gas phase compositions and reactive-ion etching kinetics for Si and SiO2 in binary CF4 + Ar and C4F8 + Ar gas mixtures were studied under conditions of 13.56 MHz inductive RF discharge. As fixed input parameters, we used the total pressure of feed gas (6 mTorr) as well as power levels supplied by plasma excitation source (700 W) and bias source (200 W). The investigation approach combined plasma diagnostics experiments with double Langmuir probe and 0-dimensional (global) model for the chemistry of neutral species. It was shown that investigated gas mixtures exhibit quite close properties in respect to both ions-related parameters and electron gas while are characterized by sufficient differences in kinetics of atoms and radicals. The features of C4F8 + Ar gas under the given set of processing conditions are the higher density of polymerizing radicals, the lower density of F atoms as well as the weaker sensitivity the last parameter to the change in Ar fraction in a feed gas. Etching experiments indicated that a) an increase in Ar fraction in CF4 + Ar and C4F8 + Ar gas mixtures results in qualitatively different changes in Si and SiO2 etching rates; and b) obtained dependencies of etching rates on Ar fraction in both gas mixtures contradict with the behavior of F atom flux. Obviously, such situation corresponds to the change in reaction probability of F atoms with the treated surface. It was suggested that an increase of Ar fraction in the low-polymerizing CF4 + Ar plasma activates the heterogeneous chemical reaction through the intensification of ion-stimulated desorption of etching products and/or surface amorphization. The similar effect for the high-polymerizing C4F8 + Ar plasma may be related to decreasing fluorocarbon film thickness that provides the better access of F atoms to the etched surface.
Vulvar vestibular papillomatosis: All genital lesions are not sexually transmitted diseases
Authors: Pathak Thapa Deeptara
Published: May 2021

Vulvar vestibular papillomatosis (VVP) is considered as normal anatomical variant of the vulva. A 19-year-old female presented with asymptomatic pinkish filliform papules symmetrically distributed on vulva. She denied having any sexual exposure. Clinical differential diagnosis included genital wart and vestibular papillomatosis, however biopsy was consistent with Vestibular papillomatosis. PAS stain was negative. Application of 5% acetic acid did not show any change in color. We report this case to create awareness about normal variant of vulva and unnecessary exaggerated treatment and proper counseling of patient to decrease psychological trauma and associated venereophobia.
Examples of Four- or Six-Dimensional Symplectic-Haantjes Manifolds and About a Relationship with Recursion Operators
Authors: Takeuchi Tsukasa
Published: May 2021

Certain ways of characterizing integrable systems with $(1,1)$-tensor field have been investigated, so far. For example, recursion operators and Haantjes operators are known. We show that geometrical examples of four- or six-dimensional symplectic Haantjes manifolds and recursion operators for several Hamiltonian systems. Through these examples, we consider the relation between recursion operators and Haantjes operators.
$4+1$-Moulton Configuration and Positive Mass Deformation
Authors: Yoshimi Naoko , Yoshioka Akira
Published: May 2021

For given $k$ bodies of collinear central configuration of Newtonian $k$-body problem, we ask whether one can add another body on the line without changing the configuration and motion of the initial bodies so that the total $k+1$ bodies provide a central configuration. The case $k=4$ is analyzed. We study the inverse problem of five bodies and obtain a global explicit formula. Then using the formula we find there are five possible positions of the added body and for each case the mass of the added body is zero. We further consider to deform the position of the added body without changing the positions of the initial four bodies so that the total five bodies are in a state of central configuration and the mass of the added body becomes positive. For each solution above, we find such a deformation of the position of the added body in an explicit manner starting from the solution.
Star Mittag-Leffler Function
Authors: Yoshioka Akira
Published: May 2021

Star product for functions of one variable is given. A deformation of the Mittag-Leffler functions is suggested by means of the star product.
On the Noncommutative Feynman Problem
Authors: Acatrinei Ciprian Sorin
Published: May 2021

We extend the Feynman derivation of the Maxwell-Lorentz equations to the case in which coordinates do not commute, adding significantly to previous results. New dynamics is pinned down precisely both at the level of the homogeneous equations and for the Lorentz force, for which a complete derivation is given for the first time.
The severity of microstrokes depends on local vascular topology and baseline perfusion
Authors: Schmid Franca , Conti Giulia , Jenny Patrick , Weber Bruno
Published: May 2021

Cortical microinfarcts are linked to pathologies like cerebral amyloid angiopathy and dementia. Despite their relevance for disease progression, microinfarcts often remain undetected and the smallest scale of blood flow disturbance has not yet been identified. We employed blood flow simulations in realistic microvascular networks from the mouse cortex to quantify the impact of single-capillary occlusions. Our simulations reveal that the severity of a microstroke is strongly affected by the local vascular topology and the baseline flow rate in the occluded capillary. The largest changes in perfusion are observed in capillaries with two inflows and two outflows. This specific topological configuration only occurs with a frequency of 8%. The majority of capillaries have one inflow and one outflow and is likely designed to efficiently supply oxygen and nutrients. Taken together, microstrokes bear potential to induce a cascade of local disturbances in the surrounding tissue, which might accumulate and impair energy supply locally.
Calibration of cell-intrinsic interleukin-2 response thresholds guides design of a regulatory T cell biased agonist
Authors: Glassman Caleb R , Su Leon , Majri-Morrison Sonia S , Winkelmann Hauke , Mo Fei , Li Peng , Pérez-Cruz Magdiel , Ho Peggy P , Koliesnik Ievgen , Nagy Nadine , Hnizdilova Tereza , Picton Lora K , Kovar Marek , Bollyky Paul , Steinman Lawrence , Meyer Everett , Piehler Jacob , Leonard Warren J , Garcia K Christopher
Published: May 2021

Interleukin-2 is a pleiotropic cytokine that mediates both pro- and anti-inflammatory functions. Immune cells naturally differ in their sensitivity to IL-2 due to cell type and activation state-dependent expression of receptors and signaling pathway components. To probe differences in IL-2 signaling across cell types, we used structure-based design to create and profile a series of IL-2 variants with the capacity to titrate maximum signal strength in fine increments. One of these partial agonists, IL-2-REH, specifically expanded Foxp3+ regulatory T cells with reduced activity on CD8+ T cells due to cell type-intrinsic differences in IL-2 signaling. IL-2-REH elicited cell type-dependent differences in gene expression and provided mixed therapeutic results: showing benefit in the in vivo mouse dextran sulfate sodium (DSS) model of colitis, but no therapeutic efficacy in a transfer colitis model. Our findings show that cytokine partial agonists can be used to calibrate intrinsic differences in response thresholds across responding cell types to narrow pleiotropic actions, which may be generalizable to other cytokine and growth factor systems.
R7 photoreceptor axon targeting depends on the relative levels of lost and found expression in R7 and its synaptic partners
Authors: Douthit Jessica , Hairston Ariel , Lee Gina , Morrison Carolyn A , Holguera Isabel , Treisman Jessica E
Published: May 2021

As neural circuits form, growing processes select the correct synaptic partners through interactions between cell surface proteins. The presence of such proteins on two neuronal processes may lead to either adhesion or repulsion; however, the consequences of mismatched expression have rarely been explored. Here, we show that the Drosophila CUB-LDL protein Lost and found (Loaf) is required in the UV-sensitive R7 photoreceptor for normal axon targeting only when Loaf is also present in its synaptic partners. Although targeting occurs normally in loaf mutant animals, removing loaf from photoreceptors or expressing it in their postsynaptic neurons Tm5a/b or Dm9 in a loaf mutant causes mistargeting of R7 axons. Loaf localizes primarily to intracellular vesicles including endosomes. We propose that Loaf regulates the trafficking or function of one or more cell surface proteins, and an excess of these proteins on the synaptic partners of R7 prevents the formation of stable connections.
Single-cell transcriptome analysis defines heterogeneity of the murine pancreatic ductal tree
Authors: Hendley Audrey M , Rao Arjun A , Leonhardt Laura , Ashe Sudipta , Smith Jennifer A , Giacometti Simone , Peng Xianlu L , Jiang Honglin , Berrios David I , Pawlak Mathias , Li Lucia Y , Lee Jonghyun , Collisson Eric A , Anderson Mark S , Fragiadakis Gabriela K , Yeh Jen Jen , Ye Chun Jimmie , Kim Grace E , Weaver Valerie M , Hebrok Matthias
Published: May 2021

To study disease development, an inventory of an organ's cell types and understanding of physiologic function is paramount. Here, we performed single-cell RNA-sequencing to examine heterogeneity of murine pancreatic duct cells, pancreatobiliary cells, and intrapancreatic bile duct cells. We describe an epithelial-mesenchymal transitory axis in our three pancreatic duct subpopulations and identify osteopontin as a regulator of this fate decision as well as human duct cell dedifferentiation. Our results further identify functional heterogeneity within pancreatic duct subpopulations by elucidating a role for geminin in accumulation of DNA damage in the setting of chronic pancreatitis. Our findings implicate diverse functional roles for subpopulations of pancreatic duct cells in maintenance of duct cell identity and disease progression and establish a comprehensive road map of murine pancreatic duct cell, pancreatobiliary cell, and intrapancreatic bile duct cell homeostasis.
Psychomotor impairments and therapeutic implications revealed by a mutation associated with infantile Parkinsonism-Dystonia
Authors: Aguilar Jenny I , Cheng Mary Hongying , Font Josep , Schwartz Alexandra C , Ledwitch Kaitlyn , Duran Amanda , Mabry Samuel J , Belovich Andrea N , Zhu Yanqi , Carter Angela M , Shi Lei , Kurian Manju A , Fenollar-Ferrer Cristina , Meiler Jens , Ryan Renae Monique , Mchaourab Hassane S , Bahar Ivet , Matthies Heinrich JG , Galli Aurelio
Published: May 2021

Parkinson disease (PD) is a progressive, neurodegenerative disorder affecting over 6.1 million people worldwide. Although the cause of PD remains unclear, studies of highly penetrant mutations identified in early-onset familial parkinsonism have contributed to our understanding of the molecular mechanisms underlying disease pathology. Dopamine (DA) transporter (DAT) deficiency syndrome (DTDS) is a distinct type of infantile parkinsonism-dystonia that shares key clinical features with PD, including motor deficits (progressive bradykinesia, tremor, hypomimia) and altered DA neurotransmission. Here, we define structural, functional, and behavioral consequences of a Cys substitution at R445 in human DAT (hDAT R445C), identified in a patient with DTDS. We found that this R445 substitution disrupts a phylogenetically conserved intracellular (IC) network of interactions that compromise the hDAT IC gate. This is demonstrated by both Rosetta molecular modeling and fine-grained simulations using hDAT R445C, as well as EPR analysis and X-ray crystallography of the bacterial homolog leucine transporter. Notably, the disruption of this IC network of interactions supported a channel-like intermediate of hDAT and compromised hDAT function. We demonstrate that Drosophila melanogaster expressing hDAT R445C show impaired hDAT activity, which is associated with DA dysfunction in isolated brains and with abnormal behaviors monitored at high-speed time resolution. We show that hDAT R445C Drosophila exhibit motor deficits, lack of motor coordination (i.e. flight coordination) and phenotypic heterogeneity in these behaviors that is typically associated with DTDS and PD. These behaviors are linked with altered dopaminergic signaling stemming from loss of DA neurons and decreased DA availability. We rescued flight coordination with chloroquine, a lysosomal inhibitor that enhanced DAT expression in a heterologous expression system. Together, these studies shed some light on how a DTDS-linked DAT mutation underlies DA dysfunction and, possibly, clinical phenotypes shared by DTDS and PD.
The hepcidin regulator erythroferrone is a new member of the erythropoiesis-iron-bone circuitry
Authors: Castro-Mollo Melanie , Gera Sakshi , Ruiz-Martinez Marc , Feola Maria , Gumerova Anisa , Planoutene Marina , Clementelli Cara , Sangkhae Veena , Casu Carla , Kim Se-Min , Ostland Vaughn , Han Huiling , Nemeth Elizabeta , Fleming Robert , Rivella Stefano , Lizneva Daria , Yuen Tony , Zaidi Mone , Ginzburg Yelena
Published: May 2021

Background:

Erythroblast erythroferrone (ERFE) secretion inhibits hepcidin expression by sequestering several bone morphogenetic protein (BMP) family members to increase iron availability for erythropoiesis.

Methods:

To address whether ERFE functions also in bone and whether the mechanism of ERFE action in bone involves BMPs, we utilize the Erfe-/- mouse model as well as β–thalassemic (Hbbth3/+) mice with systemic loss of ERFE expression. In additional, we employ comprehensive skeletal phenotyping analyses as well as functional assays in vitro to address mechanistically the function of ERFE in bone.

Results:

We report that ERFE expression in osteoblasts is higher compared with erythroblasts, is independent of erythropoietin, and functional in suppressing hepatocyte hepcidin expression. Erfe-/- mice display low–bone–mass arising from increased bone resorption despite a concomitant increase in bone formation. Consistently, Erfe-/- osteoblasts exhibit enhanced mineralization, Sost and Rankl expression, and BMP–mediated signaling ex vivo. The ERFE effect on osteoclasts is mediated through increased osteoblastic RANKL and sclerostin expression, increasing osteoclastogenesis in Erfe-/- mice. Importantly, Erfe loss in Hbbth3/+mice, a disease model with increased ERFE expression, triggers profound osteoclastic bone resorption and bone loss.

Conclusions:

Together, ERFE exerts an osteoprotective effect by modulating BMP signaling in osteoblasts, decreasing RANKL production to limit osteoclastogenesis, and prevents excessive bone loss during expanded erythropoiesis in β–thalassemia.

Funding:

YZG acknowledges the support of the National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) (R01 DK107670 to YZG and DK095112 to RF, SR, and YZG). MZ acknowledges the support of the National Institute on Aging (U19 AG60917) and NIDDK (R01 DK113627). TY acknowledges the support of the National Institute on Aging (R01 AG71870). SR acknowledges the support of NIDDK (R01 DK090554) and Commonwealth Universal Research Enhancement (CURE) Program Pennsylvania.
Avoiding culture shock with the SARS-CoV-2 spike protein
Authors: Hale Benjamin G
Published: May 2021

When culturing SARS-CoV-2 in the laboratory it is vital to avoid deletions in the gene for the spike protein that could affect the interpretation of experiments.
Humanitarian Handicrafts
Authors: Gill Rebecca , Barber Claire , Taithe Bertrand
Published: May 2021

This paper asks how craft practice can inform historical reconsiderations of handicraft produced within a humanitarian socio-economic framework (to support humanitarian aims or fund-raising initiatives), and in turn explores how historical processes become materialised in contemporary humanitarian craftwork. By considering the possibilities for practice-based methods, this paper proposes the utility of involvement in craft-making processes for historians of humanitarianism. At the same time, this gives rise to a multiplicity of concerns for a contemporary craft practitioner undertaking a form of creative expression identifiable by its humanitarian purpose. It is therefore a helpful corrective to the temptation to think that experiments are innovations. Looking at early attempts in history we see a practice mirrored, not in the results, but in the process of working in a humanitarian mode of craft-based practice.
H.D.’s Palimpsest and a weaving practice
Authors: Infeld Jordana
Published: May 2021

The relationship between text and textile is ancient and multi-faceted. This paper aims to extend this relationship by placing a weaving practice in dialogue with H.D.’s novel Palimpsest. Weaving has a distinctive relationship with time, and therefore provides fertile ground for thinking through the way time is depicted in literary fiction. Time operates in weaving at various scales and rhythms, and Palimpsest furthers this understanding of time through its own rhythms and invocations of the image of the palimpsest. Drawing on my own weaving practice, my aim is to provide an account of how a craft practice might enable a particular method of reading texts that extends beyond traditional close reading methods.
Crystals as Co-creators
Authors: Boons Sofie
Published: May 2021

Grown crystals are used for a range of novel innovations supporting a wide array of industries. Within the jewellery industry however, grown crystals are only used in a limited capacity and mainly as a surrogate for mined gemstones. This paper investigates the methodology of Crystal Growing Design, through conducting experiments testing four hypotheses developed around the practice. Through utilising a DIY approach the author investigates the opportunities and challenges presented by incorporating the methodology into her jewellery design practice. Sugar, alum and salt are experimented with to provide a theoretical experimentation of the methodology to justify the further incorporation and adaptation of more enhanced growing processes as used for the growing of gemstone quality crystals.