bluuebunny/crossref_metadata_2025 huggingface dataset:
Vitamin D Deficiency at Mid-Pregnancy Is Associated with a Higher Risk of Postpartum Glucose Intolerance in Women with Gestational Diabetes Mellitus
Authors: Kim Kyung-Soo , Park Seok Won , Cho Yong-Wook , Kim Soo-Kyung
Published: March 2020

Background: To evaluate the association between serum 25-hydroxyvitamin D (25(OH)D) at mid-pregnancy and postpartum glucose intolerance in women with gestational diabetes mellitus (GDM). Methods: We enrolled 348 pregnant women diagnosed with GDM from August 2012 to October 2016. We measured serum 25(OH)D levels at mid-pregnancy and carried out a 75-g oral glucose tolerance test at 6 to 12 weeks after delivery. Vitamin D deficiency was defined as serum 25(OH)D <20 ng/mL. Results: The prevalence of vitamin D deficiency was 76.7% (n=267). Women with vitamin D deficiency had a higher prevalence of postpartum glucose intolerance than did those without vitamin D deficiency (48.7% vs. 32.1%, P=0.011). Serum 25(OH)D level was negatively correlated with hemoglobin A1c at antepartum and postpartum period (antepartum: r=−0.186, P=0.001; postpartum: r=−0.129, P=0.047). Homeostasis model assessment of β-cell function was positively correlated with serum 25(OH)D level only postpartum (r=0.138, P=0.035). The risk of postpartum glucose intolerance was 2.00 times (95% confidence interval, 1.13 to 3.55) higher in women with vitamin D deficiency than in those without vitamin D deficiency (P=0.018). Conclusion: In women with GDM, vitamin D deficiency at mid-pregnancy is associated with an elevated risk of postpartum glucose intolerance.
Jupiter-style Jet Stability
Authors: Dowling Timothy E.
Published: March 2020

Studies of Jupiter’s zonal jets, facilitated by the two Voyager flybys, the Galileo entry probe, the Cassini flyby, and the Juno orbiter have led to two fundamental insights into inviscid shear stability that have implications for a wide range of large-scale fluid systems involving alternating shear instability. The first insight is that the analog of the Mach number for vorticity (Rossby and drift) waves, “Ma,” ensures shear stability via the criterion “Ma”−1 < 1, which includes both Kelvin–Arnol’d branches of stability, and is edged with a shock. A surprise is the well-studied first branch (KA-I), which includes as special cases the textbook shear stability theorems of Rayleigh, Kuo, Charney–Stern, and Fjørtoft, merely corresponds to “Ma”−1 < 0. The second insight is that Jupiter’s tropospheric jets achieve stability via a second branch (KA-II) strategy, a 3/4 layer, undulating control surface supplied by the dynamic topography of the planet’s deep jets, which maintains “Ma”−1 ≲ 1 via stretching vorticity. The deep jets are similarly stabilized by the spherical shape of the planet itself. Although Jupiter-style zonal jet stabilization is precluded by the torus geometry used in hot-plasma fusion reactors, it is directly applicable to the tube with ends geometry used in cool-plasma applications, including antimatter storage at high-energy colliders. In general, the lessons learned from analyzing Jupiter’s jets eliminate much of the guesswork from predicting and controlling inviscid shear instability.
The Relationship Between Optic Nerve Cup-to-Disc Ratio and Retinal Nerve Fiber Layer Thickness in Suspected Pediatric Glaucoma
Authors: Mocan Mehmet C. , Machen Lindsay , Jang Inae , Cao Dingcai
Published: March 2020

Purpose:

To evaluate the relationship between optic nerve cup-to-disc ratio and peripapillary retinal nerve fiber layer (RNFL) thickness in suspected pediatric glaucoma with large cup-to-disc ratios.

Methods:

This was a retrospective study undertaken at a single academic institution. Eighty-six eyes of 43 patients who presented with large (≥ 0.5) cup-to-disc ratios in both eyes and without elevated intraocular pressure were evaluated using spectral-domain optical coherence tomography. Global and sectoral peripapillary RNFL thickness measurements, Bruch's membrane opening size, refractive error in spherical equivalents, and intraocular pressure levels were recorded for all patients. Cup-to-disc ratios were manually derived using digital fundus images (D-cup-to-disc ratio). Parameters were compared between gender or race by
t
tests or analysis of variance. The differences in the relationship among the clinical parameters between two eyes were assessed using generalized estimation equation modeling followed by Pearson's correlation analysis.

Results:

Forty-three patients (25 boys and 18 girls) with a mean age of 9.3 ± 2.7 years (range: 5 to 15 years) were included. The mean global peripapillary RNFL thickness and the D-cup-to-disc ratio of study eyes were 99.0 ± 9.2 µm and 0.66 ± 0.03, respectively. The peripapillary RNFL thickness was found to be correlated with refractive error (
r
= 0.404;
P
= .008) and Bruch's membrane opening size (
r
= 0.410;
P
= .008) but not with cup-to-disc ratios (
r
= 0.029;
P
= .858) or patient age (
r
= −0.044;
P
= .797).

Conclusions:

In patients with suspected pediatric glaucoma who present with large cup-to-disc ratios, RNFL thickness does not correlate with the degree of optic nerve cupping. Myopic refractive errors and Bruch's membrane opening size need to be taken into consideration to prevent misinterpretation of peripapillary RNFL measurements.

[
J Pediatr Ophthalmol Strabismus
. 2020;57(2):90–96.]
Les caractères originaux de la géographie de la France
Authors: Pitte Jean-Robert
Published: March 2020

La France est une nation, une construction culturelle et politique qui a agrégé des territoires divers autour du noyau de l’Île-de-France sur une durée d’un millénaire. Elle a toujours été partagée entre forces centrifuges et forces centripètes, entre le souci de respecter la diversité régionale et la centralisation étatique et géographique dont Paris est le puissant symbole. L’ouverture sur trois mers et océans et sa position de finisterre européen, de même que son héritage romain et chrétien, ont fait de la France un pays extraverti, ouvert à de multiples influences extérieures et désireux de rayonner en Europe et dans le monde.
Regionalizações brasileiras: antigos legados e novos desafios
Authors: Haesbaert Rogério
Published: March 2020

Este artigo problematiza a regionalização brasileira a partir de questões trazidas por antigas regionalizações e dos desafios contemporâneos para sua realização. São consideradas tanto as tendências de continuidade quanto as de ruptura, seja em termos analíticos quanto da realidade empírica. São apontados alguns processos mais recentes, como o da megarregião Rio-São Paulo, o das regiões e/ou redes regionais em áreas de modernização agrícola, as regiões transfronteiriças e, sobretudo, as regionalizações “a partir de baixo”, construídas através de processos de resistência de grupos subalternos.
Ensaio sobre a relação entre Estado, políticas públicas de turismo e desenvolvimento regional no Brasil
Authors: Cruz Rita de Cássia Ariza da
Published: March 2020

A despeito das profundas mudanças que atingem diretamente os papéis do Estado no desenvolvimento econômico, social e político das nações, este segue determinando “a estrutura em que ocorre a atividade pública e privada” (Hall, 2001), ou seja, a centralidade do Estado na reprodução social permanece inquestionável, incluindo-se seu protagonismo na promoção da atividade econômica do turismo. Partindo desse pressuposto, definimos como objetivo deste artigo analisar políticas públicas federais de turismo implementadas, no Brasil, no período compreendido entre 1990 e 2010, considerando os objetivos centrais das mesmas, anunciados em documentos oficiais. Entre os resultados, nos deparamos, primeiramente, com uma frágil convergência entre os objetivos norteadores das políticas analisadas. Além disso, tais objetivos privilegiam aspectos econômicos e a implementação de infraestruturas, evidenciando a promoção de processos de desvalorização do capital, promovidos pelo Estado, que, em termos de desenvolvimento regional, realizam-se numa relação dialética com o desenvolvimento geográfico desigual brasileiro.
A política dos Arranjos Produtivos Locais (APLs) e seus condicionantes socioeconômicos em regiões periféricas como o Brasil
Authors: Vignandi Rafaella Stradiotto , Neto Angelo Rondina , Abrita Mateus Boldrine
Published: March 2020

O objetivo deste trabalho é analisar a evolução da política pública baseada nos APLs para o Brasil em um período recente, considerando alguns condicionantes socioeconômicos típicos de um país classificado como periférico. Após as análises não foi possível identificar de forma clara que as políticas públicas de incentivo aos APLs no Brasil forneceram soluções efetivas para as localidades que as receberam. A contribuição do artigo foi verificar que ainda existe desigualdade na distribuição das políticas públicas pelo território brasileiro, falta de ações estratégicas e orientações claras que ajudem essas regiões periféricas a estimularem suas potencialidades locais. A política pública mostrou-se relevante para o desenvolvimento, principalmente, local; porém, ainda se encontra muito concentrada em certas regiões brasileiras.
La dynamique du marché immobilier de la ville de Buenos Aires. Le cas de « Las Cañitas » (1991-2018)
Authors: Iulita Adrián C.
Published: March 2020

L'avènement de la dictature civico-militaire en 1976 a inauguré une nouvelle étape sous la forme de « construction de la ville » en Argentine, et en particulier dans la ville autonome de Buenos Aires (CABA). Dans le présent travail, nous abordons le cas de « Las Cañitas », une zone de dix pâtés de maisons situés entre les quartiers de Palermo et de Belgrano, au nord de la ville autonome de Buenos Aires, qui ont muté avec cette « nouvelle » façon de construire la ville, à la fois dans sa structure sociale et urbaine. Nous analysons les processus qui ont permis l’émergence de cette « zone exclusive » dans la ville, depuis sa configuration comme un « pôle gastronomique à la mode » dans les années 1990 et, après la profonde crise de 2001, son positionnement en tant qu’objet privilégié au sein du marché immobilier de la ville.
A região do devir e a região do atraso. Uma leitura da região de Presidente Prudente
Authors: Sposito Eliseu Savério
Published: March 2020

A Região de Presidente Prudente pode ser interpretada por meio do território que se transforma em região. Para isso, a recuperação histórica da sua construção (território) e da conformação de um conceito (região) que conforma a compreensão do lugar como espaço do devir e espaço do atraso. A confrontação de diferentes conceitos, importantes para a Geografia, é uma possibilidade de mostrar, em parte por meio da intermediação de pronunciamentos adquiridos em um meio de comunicação (jornal), como se forma o discurso que se consolida e marca, de maneira quase permanente, seu contorno simbólico e os elementos geográficos que o compõem. Nisso se incorporam aspectos da cultura, da economia, da dinâmica populacional e da paisagem que se entrelaçam ao longo do processo histórico de ocupação de parte do oeste do Estado de São Paulo.
Regionalización de las migraciones residenciales interurbanas en Chile en el período 1997‑2002
Authors: Escolano‑Utrilla Severino , Ortiz-Véliz Jorge , Moreno-Mora Rodrigo
Published: March 2020

Los cambios de residencia interurbanos constituyen una manifestación de las interacciones entre ciudades de un sistema urbano. Los flujos migratorios conforman una red única y organizada, que emerge de las prácticas de los migrantes. La aplicación combinada de métodos de análisis de redes y análisis espacial a microdatos censales, ha permitido caracterizar la estructura de la red de flujos migratorios interurbanos en Chile en el quinquenio 1997-2002. Los resultados muestran que las migraciones residenciales interurbanas constituyen una red de flujos heterogéneos en cuanto a su magnitud y alcance espacial, pero su combinación genera una estructura jerarquizada y muy estable, compuesta por grupos de ciudades con fuertes interconexiones migratorias mutuas. La proximidad geográfica es uno de los factores más importantes que conforman esta estructura, junto con la dinámica territorial de la economía y la distribución y jerarquía de las infraestructuras de transportes y comunicaciones.
Onde está a paisagem nas políticas ambientais e territoriais do México?
Authors: Checa-Artasu Martín Manuel
Published: March 2020

No México, o estudo da paisagem como conceito, e seu uso como ferramenta de análise no contexto das políticas públicas territoriais e ambientais ainda é muito escasso. No entanto, nos últimos anos têm surgido distintas monografias e artigos e se tem realizado distintos congressos que tentaram, desde diferentes disciplinas das ciências sociais, as ciências do design e das humanidades, colocar a paisagem como um elemento de debate acadêmico.Desligado desse debate, desde os tomadores de decisões de políticas públicas do governo anterior, algumas propostas foram feitas, como a “Estrategia hacia el 2040” [“Estratégia para 2040”] da Comisión Nacional de Áreas Naturales Protegidas [“Comissão Nacional das Áreas Naturais Protegidas”], ou a modificação da Ley General de equilibrio ecológico y protección al ambiente [“Lei Geral do equilíbrio ecológico e proteção ao meio ambiente”], o que dava a possibilidade de nomear paisagens bioculturais como área natural protegida, e que com a chegada ao poder de López Obrador, ficaram paradas. São iniciativas que aparentemente faziam da paisagem um objeto analítico e de gestão pública, mas, infelizmente, elas estão desligadas da própria teoria da paisagem, dos inquéritos que são feitos desde a academia e até mesmo, são de aplicabilidade questionável tanto legal como operacional, porque parecem mais resultado de conjunturas particulares ou de modas, e de certas posições setoriais.O resultado é que a paisagem ainda é um dos grandes esquecidos nas políticas ambientais e territoriais do México, apesar dos graves problemas que existem no país e ainda tem uma consideração muito insuficiente no quadro jurídico. O trabalho que apresentamos pretende enfatizar as causas desse esquecimento, que resultam em uma escassa cultura da paisagem visível em muitas áreas, como a concepção das propostas já citadas e que requer de estratégias urgentes para seu redimensionamento, que passam através do campo da educação, da valorização da arquitetura paisagística e da análise de conflitos territoriais para sua correta posta em prática nas políticas públicas.
Elementos para a apreensão da dimensão regional do urbano-metropolitano na atualidade
Authors: Freitas-Firkowski Olga Lúcia Castreghini de
Published: March 2020

A dimensão regional ganha destaque nas proposições contemporâneas que visam compreender a realidade urbano-metropolitana. Isso porque a urbanização tem produzido novas expressões espaciais nas últimas décadas, parte delas, apreendida por meio de uma diversidade de conceitos nos quais a região tem destaque, pode se apontar: cidade-região, megarregião e arranjo urbano-regional, além de outros onde a dimensão regional – embora não explicitamente - está presente, como é o caso dos corredores urbanos e das megalópoles. Tais conceitos são fruto da crescente complexidade das metrópoles e evidenciam as imensas proporções que tais espacialidades têm alcançado. Do ponto de vista teórico, é fundamental reconhecer a dimensão regional dessas novas espacialidades urbano-metropolitanas, e do ponto de vista aplicado, faz-se mister operar novos indicadores e variáveis que resultem em leituras adequadas dessa realidade e contribuam para revelar as dinâmicas de nosso tempo. Dessa forma, o presente artigo visa recuperar algumas proposições teóricas e seu conteúdo aplicado, além de apresentar dois trabalhos recentes, respectivamente, os arranjos populacionais do IBGE (2015) e as escalas de urbanização brasileira (Moura; Oliveira; Pêgo, 2018), que oferecem novas possibilidades de incrementar a análise espacial, ultrapassando as clássicas divisões do território e inserindo uma variedade de novos elementos que devem ser observados.
Pandemia de COVID-19, as fronteiras pelo mundo e o transporte aéreo na Itália
Authors: Neto Thiago Oliveira , Garcia Tatiana de Souza Leite , Spinussi Eduardo
Published: March 2020

A COVID-19, classificada como epidemia em dezembro de 2019 na China, transcendeu as fronteiras e atingiu pessoas em outras regiões do mundo, levando a Organização Mundial da Saúde a classificá-la como pandemia, em março de 2020. A propagação dessa doença em escala global e os efeitos negativos em várias dimensões, impactaram as relações humanas, comerciais, econômicas, políticas e os fluxos nos espaços geográficos. No momento desse contexto, esse texto busca descrever, através de figuras cartográficas, fotográficas e gráficas, as condições das fronteiras pelo mundo e do transporte aéreo na Itália.
Electrochemical Performance of Nanocrystalline Zinc Ferrite Films Synthesized Using Electrodeposition
Authors: Elsayed E. Mostafa , Rashad Mohamed M. , Khalil H.F.Y. , Hussein M.R. , El-Sabbah M.M.B. , Ibrahim I.A.
Published: March 2020

Nanocrystalline spinel zinc ferrite ZnFe2O4 thin film has been studied and synthesized via the electrodeposition-anodization process. Electrodeposited ZnFe2 alloys were obtained from aqueous sulphate bath. The resulted alloys were electrochemically oxidized in strong alkaline solution (1 M KOH) at room temperature to the analogous hydroxides. The electroanodized ZnFe2 alloy film was annealed in air at 400 °C for 2 h to get the required zinc ferrite. The electrochemical factors controlling of the electrodeposition of ZnFe2 alloys such as the bath temperature, agitation, the current density were studied and optimized. The crystal structure, crystal size and microstructure of the produced ferrites were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The deposited film was mainly composed of ZnFe2O4 based on XRD studies. The produced film had a spinel structure and the crystallite size was 4.9 nm. SEM micrograph of the resulted zinc ferrite particles shows compact crystallites shapes and agglomerated chains with smallest semicircular particles like morphology.
Effect of Welding Processes on Mechanical and Microstructural Characteristics of DP780 Steel Welded Joints for the Automotive Industry
Authors: Hafez Khalid M. , Ghanem Mohamed Mosalam , Abdel-Aleem Hamed A. , Fathy Naglaa
Published: March 2020

Arc welding processes are widely used in the automotive industry among other welding processes. Consequently, laser welding technology is being used instead of arc welding due to the rapid heating and cooling characteristics of the laser. In this study, empirical investigations and comparative study are held out on the arc and laser beam welded joints of DP780 dual-phase steel. Accordingly, weld joint microstructures, hardness distribution, and fatigue properties cross the butt-welded joints were investigated. The results showed that laser beam welding produces narrow fusion and heat-affected zones while gas metal arc welding produced wide welds with incomplete penetration. It was observed that the microstructure of the laser joint weld metal has mainly lath martensite in the ferritic matrix, while microstructure of gas metal arc weld metal relies upon filler type. Heat-affected zone in DP780 steel exhibit hardness softening in both laser beam welding and gas metal arc welding due to martensite tempering, a wider softening region was clearly observed in heat-affected zone welded by gas metal arc welding than laser beam welding. Generally, fatigue ratio, fatigue limit and fatigue life of the welded joints were improved by using laser welding.
Stress Corrosion Cracking of High-Pressure Scrubber in Urea Plant: A Case Study
Authors: Ghanem Mohamed Mosalam , Abdul Aleem Hamed A. , Hafez Khalid M.
Published: March 2020

This current work investigates the failure of high pressure (HP) scrubber lining in urea fertilizer production plant after 20 years in service. AISI 316L urea grade (UG) stainless steel scrubber lining was showed severe damage. In order to find out the root cause of failure, cracks were observed by visual inspection together with microstructure examination Chemical analysis of the base metal and corrosion products were analyzed Chemical analysis of the lining base alloy is conformed to the AISI 316L UG. Results revealed existence of chloride assisted stress corrosion cracking (SCC) initiated from pitting formed in the inner surface of the scrubber lining. Corrosion products analysis revealed existence of chloride (Cl-). Localized pitting corrosion is attributed to Cl attack. The expected sources of chloride are water during hydrostatic testing, water vapor during passivation, chloride containing atmosphere during transportation or storage the base alloy in coastal areas and water vapor in carbamate gasses (process fluid). Pits initiated at the lining inner surface act as stress concentration sites assisted SCC initiation. Chloride SCC is caused by simultaneous action of both tensile stresses and a corrosive environment containing chloride. To overcome the scrubber failure, chloride must be eliminated and residual stresses must be controlled. Upgrading the scrubber base alloy using high-alloy duplex stainless steel (Safurex) is highly recommended.
LiMn1.5Ni0.25Fe0.2M0.05O4 Nanoparticles as a Cathode Material for Rechargeable Li-Ion Batteries
Authors: Abdellatif Haitham A. , Sanad Mostafa M.M. , Elnaggar Elsayed M. , Rashad Mohamed M. , El-Kady Gamal M.
Published: March 2020

New series of spinel LiNi0.25Fe0.2Mˊ0.05Mn1.5O4 (Mˊ = Cu, Mg or Zn) cathode materials have been purposefully tailored using sol-gel auto-combustion method at low annealing temperature ~ 700°C for 3 h. The XRD analysis showed that all substituted (LNFMO-Mˊ) samples are comported with the main structure of undoped (LNFMO) with crystalline disordered spinel Fd-3m structure. TEM images revealed the octahedron-shape like morphology for the particles and the LNFMO-Zn sample has the widest particle size distribution. EIS spectra evidenced that a typical one semicircle (LNFMO-Mg) was revealed for each cell, suggesting the absence of ionic conductivity contribution. The values of charge transfer resistance (Rct) were equal to 9.3, 6.7, 6.0 and 4.4 kΩ for LNFMO, LNFMO-Cu, LNFMO-Mg indicating that the Zn-doped sample has the fastest kinetic diffusion rate and lowest activation energy of conduction.
Microstructure and Wear Behavior of Squeezed Magnesium Alloy (AM100) Based Composites Reinforced with ZrB2, Graphite and Hybrid of ZrB2 and Graphite Particles
Authors: El-Khair Malak Abou , Firouz Fatma , Lotfy Ahmed , Mohamed Essam , Daoud Atef
Published: March 2020

An attempt has been made to investigate the microstructures and wear behavior of magnesium alloy AM100 (Mg-Al-Mn) based composites reinforced with 7 vol. % of ZrB2, graphite or hybrid of (1:1) ZrB2 and graphite particles as well as the unreinforced magnesium alloy. Magnesium alloy was melt under shield of inert gases and composites were prepared using stir casting method. Optical microscopy was used to study the microstructures of the unreinforced alloy and composites. The composites characterized primarily by the uniform distribution of particles in the matrix and a good adherence between the particles and matrix. XRD analysis was used to identify the phases of the unreinforced alloy and composites. The XRD diffraction pattern of AM100 matrix reveals different phases, namely, Mg, AlMn and Al12Mg17. Formation of these phases is due to the reaction between alloy constituents. Dry sliding wear tests were conducted by using a pin-on-ring apparatus. The wear rates of the composites and matrix alloy were measured at loads of 10, 20 and 30 N, and sliding speed of 0.7 m/s. The worn surfaces of the composite pins were examined by scanning electron microscopy (SEM). The experimental results of the wear tests showed that the magnesium based composites exhibited higher wear rate at all the applied loads when compared to those of the unreinforced magnesium alloy. The ZrB2 reinforced magnesium composite exhibited the lowest wear rate amongst the composites material investigated in the present work.
Structural, Optical and Microstructural Properties of TiNi Thin Films before and after Oxidation
Authors: Abouarab Hanan , Kassry Amal , El-Mahallawi Iman
Published: March 2020

The deposition of composites with tailored optical properties is investigated. This would employ structures consisting of combined metallic and oxides nature. A thin layer of TiNi is obtained by using RF magnetron sputtering on a stainless-steel substrate, followed by oxidation at 400°C and 800°C for four and one hours, respectively. The optical properties of the thin films were characterized by optical spectrophotometer, and Fourier Transform Infrared Spectroscopy (FTIR). The morphology, topography, and structure were studied by scanning electron microscope (SEM), atomic force microscope (AFM), and X-ray diffraction (XRD). The results show that TiO2 has been produced through the oxidation process of the sputter-deposited TiNi thin film at high oxidation temperature. The TiNi thin films showed a significant improvement in optical properties after oxidation, as the absorbance increased, and the emittance was reduced. This work introduces oxidized TiNi thin films as candidates for solar selective absorber.
Characteristics of Ni- Cr Binary Alloys Produced by Conventional Powder Metallurgy
Authors: Mohamed Lamiaa Z. , El Kady Omayma A. , Lotfy Mohamed. M. , Ahmed Hafiz A. , Elrefaie Fawzi A.
Published: March 2020

The characteristics of Ni-Cr porous alloys containing 0.5 wt%Cr up to 12 wt%Cr were determined. The alloys were prepared from a mix of Ni-particles with filamentary shape and Cr-particles with irregular shape which then mixed with 0.5 wt% paraffin wax as a binder. The samples were formed by compaction and then sintered at 1200 °C for 1 h. The microstructure of samples was found to consist of a Ni-Cr solid solution matrix with X-ray energy dispersive analysis of Cr% less than 0.33 wt%. The matrix microstructure which composed of equiaxed grains (20-60 μm) surrounded high Cr content islands which also contained γ phase (Ni2.88 Cr1.22). The apparent density of the alloys was found to decrease with Cr content from 8.32 g/cm3 for samples containing 0.5 wt%Cr to 7.26 g/cm3 for samples containing 12 wt%Cr. Therefore, the estimated porosity was found to increase from 6.4% to 16.6% with increasing Cr content from 0.5 wt% to 12 wt%. The microhardness of the samples varied from 153.6 to 284.2 VHN for the equiaxed grains and from 119.6 to 240.6 VHN for the island areas.
Effect of Cooling Rate and Aging Process on Wear Behavior of Deformed TC21 Ti-Alloy
Authors: Elshaer Ramadan N. , Ibrahim Khaled M. , Lotfy Ibrahim , Abdel-Latif Mahmoud
Published: March 2020

TC21 with a composition of Ti-6Al-3Mo-1.9Nb-2.2Sn-2.2Zr-1.5Cr is considered a new titanium alloy that is used in aerospace applications as a replacement for the famous Ti-6Al-4V alloy due to its high strength-to-weight ratio, high operating temperature and corrosion resistance. In this study, two different solution treatment techniques were applied on TC21 samples. Solution treatment was applied using two step heating at 1000/800 °C for 15 min each and then cooled using water quenching or air cooling to see the effect of cooling rate on microstructure as well as mechanical properties. The solution treated samples were divided into two groups; one was tested as solution treated samples without aging. While, the second group was aged at 575 °C for 4 hrs. Maximum hardness of 442 HV was observed for the water quenched and aged samples, while the minimum hardness of 340 HV was obtained for water quenched samples without aging. The lowest wear rate was obtained for water quenched and aged samples. However, the highest wear rate was reported for the samples solution treated and water quenched without aging.
Coal Desliming Using Annular Rinse Water Hydrocyclone
Authors: Tao You Jun , Zhao You Nan , Xian Yu Shuai , Song Ao , Wang Yi Peng , Shi Zheng Xiang
Published: March 2020

The separation of fine coal can be improved by pre-desliming, which was significantly enhanced when fine coal was processed using a Falcon concentrator, and <45-μm coal slime was removed. Ultrafine classification tests using Krebs classification cyclone with annular rinse water showed that the increase in feeding concentration negatively affected the efficiency of classification while increasing the classification size because the settling was hindered by the high underflow concentrations. The optimization experiments with response indicators of classification efficiency based on orthogonal design using Design-Expert software indicated that the optimal classification efficiency reached 91.32% with a feeding pressure of 0.03 MPa, a rinse water pressure of 0.02 MPa, and a feeding concentration of 12.5%. Meanwhile, the classification size was 49.99 μm, which agreed well with the predicted value.
Effect of Metallurgical Waste Properties on Determining Suitable Recycling Method
Authors: Omran Mamdouh , Fabritius Timo , Abdelrahim Ahmed
Published: March 2020

Recycling of solid waste generated from metallurgical industries will avoid disposal of wastes, enhance the use of secondary raw material fines and save costs. Numerous hydrometallurgical and pyrometallurgical processes, or a combination of both, have been proposed for the utilization of metallurgical waste. Due to insufficient knowledge of the properties of these wastes, most of these attempts still have some technical difficulties. Investigation the properties of metallurgical waste is needed before choosing the suitable recycling process.The present work describes the chemical, morphological and mineralogical properties of blast furnace sludge (BFS) and basic oxygen furnace sludge (BOFS) produced in steel plants in Finland. The investigations indicated that BFS and BOFS show significant contents of iron and coke. The sludges also contain considerable concentrations of unwanted elements such as Zn. The authors propose that microwave dezincing followed by briquetting or pelletization represent a potential method for sludges recycling. Owing to high Fe and C content it can be utilized as self-reducing material.
Thin Films in Triboelectric Nanogenerators for Blue Energy Harvesting: Fabrication, Characterization, and Modeling
Authors: Shabana Yasser M. , Mohamed Gehad Genidy , Ibrahim Ahmed , Abbas Mohamed , Mohie Mohamed , Elhusseiny Mohamed , Gamal Menna , Ahmed Mohamed , Ahmed Aya , Khaled Mohamed , Magdy Alaa
Published: March 2020

Renewable energy attracts many researchers as the non-renewable one has negative environmental impacts and limited availability. One of the main types of renewable energy is the blue energy where electricity is generated by water waves using triboelectric nanogenerators (TENGs). Thin films play an important role in the performance and therefore the efficiency of TENGs as they represent the electrodes between which electrons move producing electricity. In order to increase the generated electricity from TENGs, the properties of these electrodes should be modified. Therefore, in this paper, nano- and micro-size thin films are fabricated and characterized by measuring the geometrical parameters and electrical properties. Thin films are fabricated using aluminum with thicknesses 0.5 μm and 1.5 μm on acrylic substrate and 0.5 μm copper film on different types of dielectric materials including PVC and polystyrene. Atomic force microscopy is used to measure the geometrical parameters of the fabricated films including thickness and surface roughness. Also, Gwyddion software is used for the grain size evaluation. On the other hand, Keithley is used for measuring the electrical properties including electrical conductivity and sheet resistance. It is found that the electrical conductivity of aluminum films is inversely proportional to the thickness. The corresponding measured values of the electrical conductivity of the fabricated thinner and thicker aluminum films equal 1.7 x 107 (Ω.m)-1 and 1.4×107 (Ω.m)-1, respectively. Whereas, the electrical conductivity of the fabricated copper film equals 8.8×107 (Ω.m)-1. In addition, the temperature effects on the electrical conductivity are studied. Finally, simulation of a TENG using COMSOL software is accomplished in order to evaluate the electrical outputs of potential, charge, and energy.
Deposition, Characterization, Performance of Cadmium Sulfide Quantum Dots Thin Films Using SILAR Technique for Quantum Dot Sensitized Solar Cell Applications
Authors: Hamid Zeinab Abdel , Hassan H.B. , Hassan Manal A. , Mourad M. Hussein , Anwar S.
Published: March 2020

This work deals with the deposited cadmium sulfide (CdS) quantum dots thin films on transparent conductive fluorine-doped tin oxide (FTO) substrates prepared by successive ionic layer adsorption and reaction technique (SILAR). QD deposition based on SILAR is easy, cheap and effective method which improves the surface quality and performance of QD-based devices. The effect of the number of cycles of SILAR on the morphology and size of the quantum dots has been investigated. SILAR technique was adopted for the deposition of CdS on anatase TiO2 and the three main factors contributing to the performance of QDs processed by SILAR, namely the number of cycles used, the concentration of the precursor solution, and the reaction dipping time, are discussed. The structural, morphological and optical properties were studied using X-ray diffraction (XRD), Field emission scanning electron microscope (FESEM), Raman spectra analysis and UV-Vis NIR analysis, respectively. The particle size of CdS was calculated from XRD pattern using Debye Scherrer’s equation and the calculated particle size was 4.5-9.5 nm. Using CdSQDs, quantum dot sensitized solar cells (QDSSC) were fabricated on FTO substrates as being a transparent conductive oxide. Optical absorption property proved that the band gap energy value was about 2.44 eV. The result delivered from J-V curve revealed that the overall energy conversion efficiency increased with increasing the deposition cycles giving the best efficiency of 2.73 % at 7 cycles.
Galectin-9 and VISTA Expression Define Terminally Exhausted T Cells in HIV-1 Infection
Authors: Shahbaz Shima , Dunsmore Garett , Koleva Petya , Xu Lai , Houston Stan , Elahi Shokrollah
Published: March 2020

We report significant upregulation of Galectin-9 (Gal-9) and VISTA on both CD4+ and CD8+ T cells in HIV-infected human patients. Gal-9 and VISTA expression was associated with impaired T cells effector functions. Although Gal-9 was coexpressed with other coinhibitory receptors such as TIGIT, CD160, CD39, and VISTA, it was simultaneously coexpressed with PD-1. Coexpression of Gal-9 with PD-1 was associated with a more terminally exhausted T cell phenotype in HIV-1 patients. This was marked by higher expression of EOMES, blimp1, and Glut1 in Gal-9+ versus Gal-9− T cells, which is consistent with an exhausted T cell phenotype. Gal-9+ T cells exhibited the phenotype characteristics of effector T cells (CD45RA+, CD45RO-/lo, CD62L−, CD27lo) with higher T-bet expression. A positive correlation between the plasma viral load with the plasma Gal-9 levels in treatment-naive HIV patients and an inverse correlation between CD4 count with the frequency of CD4+Gal-9+ T cells were observed. Increased percentages of Gal-9+ T cells was evident in HIV-treated patients. Enhanced expression of Gal-9 on T cells following PMA stimulation via protein kinase C suggests persistent TCR stimulation as a potential contributing factor in Gal-9 upregulation in HIV patients. This was supported by the constant degranulation of Gal-9+ T cells. Moreover, CD44 clustering by Gal-9 may influence cytoskeleton rearrangement and coclustering of CD3, which likely impact initiation of signal transduction via TCR. Our preliminary data also confirm upregulation of Gal-9 on T cells in hepatitis B virus and HPV infections. These results demonstrate a novel role for Gal-9 and VISTA in HIV pathogenesis.
Жадные приближения произвольным множеством
Authors: Borodin Petr Anatolevich
Published: March 2020

Определяются различные алгоритмы жадных приближений элементами произвольного множества $M$ в банаховом пространстве. Исследуется сходимость этих алгоритмов в гильбертовом пространстве при различных геометрических условиях на $M$. Как следствие получаются достаточные условия плотности аддитивной полугруппы, порожденной множеством $M$.
Библиография: 12 наименований.
Análisis del equilibrio gráfico-narrativo presente en la experiencia interactiva de los videojuegos
Authors: Sancán Lapo Milton Elías
Published: March 2020

En este artículo se analizarán los conceptos que resultan de la combinación de narrativa interactiva y realismo gráfico en videojuegos. Su revisión es importante debido a la presencia de software como los motores de videojuegos o “game engines” que desde 1998 están al alcance de desarrolladores y público entusiasta. Muchos son gratuitos, sencillos de usar y con recursos para aprendizaje como videotutoriales.  Sin embargo, se halló que estudios acerca del equilibrio gráfico y narrativo en videojuegos son escasos. Para este análisis se revisó documentación teórica, declaraciones de profesionales vinculados a la industria, y ejemplos de  narrativa interactiva direccionada al entretenimiento en géneros de ficción y desde eventos reales. Se concluye que únicamente la narrativa o únicamente el realismo no activa una mejor experiencia global en videojuegos. A ese equilibrio se suma factores visuales y de interacción; cada uno con un peso diferente pero necesario según la temática y los objetivos de sus creadores.
Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010 – Part 1: Model evaluation and air mass characterization for stratosphere–troposphere transport
Authors: Itahashi Syuichi , Mathur Rohit , Hogrefe Christian , Zhang Yang
Published: March 2020

Abstract. Stratospheric intrusion and trans-Pacific transport have been recognized as a
potential source of tropospheric ozone over the US. The
state-of-the-science Community Multiscale Air Quality (CMAQ) modeling system
has recently been extended for hemispheric-scale modeling applications
(referred to as H-CMAQ). In this study, H-CMAQ is applied to study the
stratospheric intrusion and trans-Pacific transport during April 2010. The
results will be presented in two companion papers. In this Part 1 paper,
model evaluation for tropospheric ozone (O3) is presented. Observations
at the surface, by ozonesondes and airplane, and by satellite across the
Northern Hemisphere are used to evaluate the model performance for O3.
H-CMAQ is able to capture surface and boundary layer (defined as surface to
750 hPa) O3 with a normalized mean bias (NMB) of −10 %; however, a
systematic underestimation with an NMB up to −30 % is found in the free
troposphere (defined as 750–250 hPa). In addition, a new air mass
characterization method is developed to distinguish influences of
stratosphere–troposphere transport (STT) from the effects of photochemistry
on O3 levels. This method is developed based on the ratio of O3
and an inert tracer indicating stratospheric O3 to examine the
importance of photochemistry, and sequential intrusion from upper layer.
During April 2010, on a monthly average basis, the relationship between
surface O3 mixing ratios and estimated stratospheric air masses in the
troposphere show a slight negative slope, indicating that high surface
O3 values are primarily affected by other factors (i.e., emissions),
whereas this relationship shows a slight positive slope at elevated sites,
indicating that STT has a possible impact at elevated sites. STT shows large
day-to-day variations, and STT impacts can either originate from the same
air mass over the entire US with an eastward movement found during early
April, or stem from different air masses at different locations indicated
during late April. Based on this newly established air mass characterization
technique, this study can contribute to understanding the role of STT and
also the implied importance of emissions leading to high surface O3.
Further research focused on emissions is discussed in a subsequent paper (Part 2).
Modeling stratospheric intrusion and trans-Pacific transport on tropospheric ozone using hemispheric CMAQ during April 2010 – Part 2: Examination of emission impacts based on the higher-order decoupled direct method
Authors: Itahashi Syuichi , Mathur Rohit , Hogrefe Christian , Napelenok Sergey L. , Zhang Yang
Published: March 2020

Abstract. The state-of-the-science Community Multiscale Air Quality (CMAQ) modeling
system, which has recently been extended for hemispheric-scale modeling
applications (referred to as H-CMAQ), is applied to study the trans-Pacific
transport, a phenomenon recognized as a potential source of air pollution in
the US, during April 2010. The results of this analysis are presented in
two parts. In the previous paper (Part 1), model evaluation for tropospheric
ozone (O3) was presented and an air mass characterization method was
developed. Results from applying this newly established method pointed to
the importance of emissions as the factor to enhance the surface O3 mixing
ratio over the US. In this subsequent paper (Part 2), emission impacts are
examined based on mathematically rigorous sensitivity analysis using the
higher-order decoupled direct method (HDDM) implemented in H-CMAQ. The HDDM
sensitivity coefficients indicate the presence of a NOx-sensitive
regime during April 2010 over most of the Northern Hemisphere. By defining
emission source regions over the US and east Asia, impacts from these
emission sources are examined. At the surface, during April 2010, the
emission impacts of the US and east Asia are comparable over the western
US with a magnitude of about 3 ppbv impacts on monthly mean O3
all-hour basis, whereas the impact of domestic emissions dominates over the
eastern US with a magnitude of about 10 ppbv impacts on monthly mean
O3. The positive correlation (r=0.63) between surface O3 mixing
ratios and domestic emission impacts is confirmed. In contrast, the
relationship between surface O3 mixing ratios and emission impacts from
east Asia exhibits a flat slope when considering the entire US. However,
this relationship has strong regional differences between the western and
eastern US; the western region exhibits a positive correlation
(r=0.36–0.38), whereas the latter exhibits a flat slope (r < 0.1).
Based on the comprehensive evaluation of H-CMAQ, we extend the sensitivity
analysis for O3 aloft. The results reveal the significant impacts of
emissions from east Asia on the free troposphere (defined as 750 to 250 hPa)
over the US (impacts of more than 5 ppbv) and the dominance of
stratospheric air mass on upper model layer (defined as 250 to 50 hPa) over
the US (impacts greater than 10 ppbv). Finally, we estimate changes of
trans-Pacific transport by taking into account recent emission trends from
2010 to 2015 assuming the same meteorological condition. The analysis
suggests that the impact of recent emission changes on changes in the
contribution of trans-Pacific transport to US O3 levels was
insignificant at the surface level and was small (less than 1 ppbv) over the free troposphere.
Oxygenated products formed from OH-initiated reactions of trimethylbenzene: Autoxidation and accretion
Authors: Wang Yuwei , Mehra Archit , Krechmer Jordan E. , Yang Gan , Hu Xiaoyu , Lu Yiqun , Lambe Andrew , Canagaratna Manjula , Chen Jianmin , Worsnop Douglas , Coe Hugh , Wang Lin
Published: March 2020

Abstract. Gas-phase oxidation pathways and products of anthropogenic volatile organic compounds (VOCs), mainly aromatics, are the subject of intensive research with attention paid to their contributions to secondary organic aerosol (SOA) formation and potentially, new particle formation (NPF) in the urban atmosphere. In this study, a series of OH-initiated oxidation experiments of trimethylbenzene (TMB, C9H12) including 1,2,4-TMB, 1,3,5-TMB, 1,2,3-TMB, and 1,2,4-(methyl-D3)-TMBs (C9H9D3) were investigated in an oxidation flow reactor (OFR), in the absence and presence of NOx. Products were measured using a suite of state-of-the-art instruments, i.e., a nitrate-based chemical ionization – atmospheric pressure interface time-of-flight mass spectrometer (Nitrate CI-APi-TOF), an iodide-adduct chemical ionization – time-of-flight mass spectrometer (Iodide CI-TOF) equipped with a Filter Inlet for Gases and AEROsols (FIGAERO), and a Vocus proton-transfer-reaction mass spectrometer (Vocus PTR). A large number of C9 products with 1–11 oxygen atoms and C18 products presumably formed from dimerization of C9 peroxy radicals were observed, hinting the extensive existence of autoxidation and accretion reaction pathways in the OH-initiated oxidation reactions of TMBs. Oxidation products of 1,2,4-(methyl-D3)-TMBs with deuterium atoms in different methyl substituents were then used as a molecular basis to propose potential autoxidation reaction pathways. Accretion of C9 peroxy radicals is the most significant for aromatics with meta-substituents and the least for aromatics with ortho-substituents, if the number and size of substituted groups are identical. The presence of NOx would suppress the formation of C18 highly oxygenated molecules (HOMs) and enhance the formation of organonitrates, and even dinitrate organic compounds. Our results show that the oxidation products of TMB are much more diverse and could be more oxygenated than the current mechanisms predict.
Effects of AIR pollution on cardiopuLmonary disEaSe in urban and peri-urban reSidents in Beijing: protocol for the AIRLESS study
Authors: Han Yiqun , Chen Wu , Chatzidiakou Lia , Yan Li , Zhang Hanbin , Chan Queenie , Barratt Ben , Jones Rod , Liu Jing , Wu Yangfeng , Zhao Meiping , Zhang Junfeng , Kelly Frank J. , Zhu Tong ,   the AIRLESS team
Published: March 2020

Abstract. Beijing, as a representative megacity in China, is experiencing some of the most severe air pollution in the world, and its fast urbanization has led to a substantial urban and peri-urban disparities in both health status and air quality. Uncertainties remain regarding the possible causal links between individual air pollutants and health outcomes, with spatial comparative investigations of these links lacking, particularly in developing megacities. In light of this challenge, Effects of AIR pollution on cardiopuLmonary disEaSe in urban and peri-urban reSidents in Beijing (AIRLESS) was initiated with the aim of addressing the complex issue of multipollutant exposures on cardiopulmonary outcomes. The two panel studies deployed included urban and peri-urban elderly Beijing residents recruited from two established cohorts. The project was strengthened further through the measurement of an extensive range of ambient and indoor pollutants during two intensive monitoring campaigns undertaken simultaneously with the collection of health data from the panel participants. This paper presents the novel elements and methodology deployed in the AIRLESS project that addressed gaps in current understanding: namely (1) contrast of the exposure to air pollution in peri-urban and urban areas in a developing megacity, (2) a nested case (hypertensive) – control (healthy) study design to identify potential susceptible population, (3) the detailed assessments of personal exposure to air pollution in diverse indoor and outdoor environments using miniaturised portable platforms; (4) detailed assessment of the chemical composition of particulate matter; and (5) a rich collection of biological markers to understand the underlying mechanisms of health responses to air pollution.