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Tribological behaviour of AZ31 magnesium alloy reinforced by bimodal size B_(4)C after precipitation hardening

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Journal of magnesium and Alloys 2022年第11期10卷 3267-3280页

作者： Seyed Kiomars moheimani Azadeh Keshtgar saeed Khademzadeh morteza Tayebi Ali Rajaee Abdollah Saboori Advanced materials Research Center Department of Materials EngineeringNajafabad BranchIslamic Azad UniversityNajafabadIran Department of Research and Development Nejat Darya CompanyBoushehrIran Center for Risk and Reliability University of MarylandCollege ParkMD 20742United States Department of Industrial Engineering University of Padova35131 PadovaItaly Young Researchers and Elites Club Science and Research BranchIslamic Azad UniversityTehranIran Department of materials and Polymer Engineering Hakim Sabzevari UniversitySabzevarIran Integrated Additive manufacturing Center(IAm) Department of Management and Production Engineering(DIGEP)Politecnico di TorinoCorso Duca Degli Abruzzi2410129TorinoItaly

This study investigated dry sliding wear properties of AZ31 magnesium alloy and B_(4)C-reinforced AZ31 composites containing 5, 10, and 20 wt.% B_(4)C with bimodal sizes under different loadings(10-80 N) at various sliding speeds(0.1-1 m/s) via the pin-on-disc *** evaluations showed that when the distribution of B_(4)C particles was uniform the hardness of the composites increased by enhancing the reinforcement content. The unreinforced alloy and the composite samples were examined to determine the wear mechanism maps and identify the dominant wear mechanisms in each wear condition and reinforcement content. For this purpose, wear rates and friction coefficients were recorded during the wear tests and worn surfaces were characterized by scanning electron microscopy and energy dispersive X-ray spectrometry analyses. The determined wear mechanisms were abrasion, oxidation, delamination, adhesion, and plastic deformation as a result of thermal softening and melting. The wear evaluations revealed that the composites containing 5 and 10 wt.% B_(4)C had a significantly higher wear resistance in all the conditions. However, 20 wt.% B_(4)C/AZ31 composite had a lower resistance at high sliding speeds(0.5-1 m/s) and high loadings(40-80 N) in comparison with the unreinforced alloy. The highest wear resistance was obtained at high sliding speeds and low loadings with the domination of oxidative wear.

关键词： B_(4)C AZ31 alloy metal matrix composite Wear mechanism Bimodal

Effect of changing mesopic and photopic light conditions on visual functions

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International Journal of Ophthalmology(English edition) 2023年第8期16卷 1287-1292页

作者： Fatemeh mosayebi Seyyed mehdi Tabatabaee Haleh Kangari saeed Rahmani Department of Optometry School of RehabilitationShahid Beheshti University of Medical SciencesTehran 19839-63113Iran Department of Biostatistics School of RehabilitationShahid Beheshti University of Medical SciencesTehran 19839-63113Iran

AIm:To determine the effects of change in light conditions on refractive error and visual functions including visual acuity,stereopsis and contrast ***:This cross-sectional study was conducted in the optometry clinic of the Shahid Beheshti School of Rehabilitation on 48 students in *** of them had eye health and normal visual function and could have refractive errors or *** intensity of 4 lx was considered equivalent to photopic light condition and light intensity of 1 lx was considered to be equivalent to mesopic light *** amount of refractive error was checked by auto refractometer and its changes in mesopic light condition were subjectively ***,visual acuity,stereopsis and contrast sensitivity(in five spatial frequencies of 1.5,3,6,12,and 18 cycles per degree),were measured first in photopic light condition and then in mesopic light condition,by Snellen control vision chart,stereo butterfly test and the m&S technology monitor test ***:In the 48 student subjects with an average age of 22.69±3.56y,mean of refractive error as sphere equivalent,visual acuity and stereopsis were-1.25±1.74 diopters,0 logmAR,44.37±13.03 seconds of arc,respectively in photopic light condition while in mesopic light was equal to-1.56±1.75 diopters,0.12±0.09 logmAR and 50.62±33.35 seconds of arc,*** mean of contrast sensitivity measured at spatial frequencies of 1.5,3,6,12,and 18 cycles per degree in photopic condition was equal to 2.38±0.04,2.37±0.07,2.04±0.21,1.27±0.32,0.82±0.27 logarithm of contrast sensitivity,respectively and in mesopic lighting condition was equal to 2.34±0.12,2.30±0.16,1.84±0.28,1.02±0.28,0.63±0.24 logarithm of contrast sensitivity,*** analysis showed a significant difference between the two lighting conditions in all evaluated variables[refractive error(P<0.001),visual acuity(P<0.001),stereopsis(P=0.008)and contrast sensitivity(P<0.001)].CONCLUSION:The refractive

关键词： mesopic light condition photopic light condition visual performance visual acuity stereopsis contrast sensitivity visual functions

Effect of Bohm quantum potential in the propagation of ion–acoustic waves in degenerate plasmas

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Chinese Physics B 2016年第10期25卷 222-229页

作者： m m hasan m A Hossen A Rafat A A mamun Department of Physics Jahangirnagar University

A theoretical investigation has been carried out on the propagation of the ion–acoustic(IA) waves in a relativistic degenerate plasma containing relativistic degenerate electron and positron fluids in the presence of inertial non-relativistic light ion fluid. The Korteweg-de Vries(K-dV), modified K-dV(m K-dV), and mixed m K-dV(mm K-dV) equations are derived by adopting the reductive perturbation method. In order to analyze the basic features(phase speed, amplitude, width,etc.) of the IA solitary waves(SWs), the SWs solutions of the K-dV, m K-dV, and mm K-d V are numerically analyzed. It is found that the degenerate pressure, inclusion of the new phenomena like the Fermi temperatures and quantum mechanical effects(arising due to the quantum diffraction) of both electrons and positrons, number densities, etc., of the plasma species remarkably change the basic characteristics of the IA SWs which are found to be formed either with positive or negative potential. The implication of our results in explaining different nonlinear phenomena in astrophysical compact objects, e.g.,white dwarfs, neutron stars, etc., and laboratory plasmas like intense laser–solid matter interaction experiments, etc., are mentioned.

关键词： Bohm quantum potential degenerate relativistic plasma electron and positron quantum effect

Investigation of role of cartilage surface polymer brush border in lubrication of biological joints

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Friction 2022年第1期10卷 110-127页

作者： JinJing LIAO David W.SmITH saeed mIRAmINI Bruce S.GARDINER Lihai ZHANG Department of Infrastructure Engineering.The University of melbourne.Victoria 3010 Australia Faculty of Engineering and mathematical Sciences The University of Western AustraliaWA 6009Australia College of Science Health.Engineering and Education.Murdoch UniversityWA 6150Australia

Although experimental evidence has suggested that the polymer brush border(PBB)on the cartilage surface is important in regulating fluid permeability in the contact gap,the current theoretical understanding of joint lubrication is still *** address this research gap,a multiscale cartilage contact model that includes PBB,in particular its effect on the fluid permeability of the contact gap,is developed in this *** modeling is employed to estimate the permeability of the contact *** permeability is classified into two categories:For a gap size>1μm,the flow resistance is assumed to be dominated by the cartilage roughness;for gap sizem,flow resistance is assumed to be dominated by the surface polymers extending beyond the collagen network of the articular *** gap sizes of less than 1μm,the gap permeability decreases exponentially with increasing aggrecan concentration,whereas the aggrecan concentration varies inversely with the gap ***,the gap permeability is employed in a macroscale cartilage contact model,in which both the contact gap space and articular cartilage are modeled as two interacting poroelastic *** fluid exchange between these two media is achieved by imposing pressure and normal flux continuity boundary *** model results suggest that PBB can substantially enhance cartilage lubrication by increasing the gap fluid load support(e.g.,by 26 times after a 20-min indentation compared with the test model without a PBB).Additionally,the fluid flow resistance of PBB sustains the cartilage interstitial fluid pressure for a relatively long period,and hence reduces the vertical deformation of the ***,it can be inferred that a reduction in the PBB thickness impairs cartilage lubrication ability.

关键词： assumed polymer hence

Hepatic involvement in children with acute bronchiolitis

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World Journal of Hepatology 2022年第10期14卷 1907-1919页

作者： hasan m Isa Asma Z hasan Sara I Khalifa Sana S Alhewaizem Abdulrahman D mahroofi Fatema N Alkhan mohammed Al-Beltagi Department of Pediatrics Salmaniya Medical ComplexManama 12Bahrain Department of Pediatrics Arabian Gulf UniversityManama 26671Bahrain Department of Pediatrics Sulwan Psychiatric HospitalManama 973Bu QuwahBahrain Department of Pediatrics Dream Reem Medical CenterMuharraq 50573Bahrain Department of Pediatrics King Hamad University HospitalMuharraq 24343Bahrain Department of Pediatrics Faculty of MedicineTanta UniversityTanta 31527AlgharbiaEgypt Department of Pediatrics University Medical CenterKing Abdulla Medical CityArabian Gulf UniversityManama 26671Bahrain Department of Pediatrics University Medical CenterDr.Sulaiman Al-Habib Medical GroupBahrainManama 26671Bahrain

BACKGROUND Respiratory syncytial virus(RSV)is a prevalent cause of lower respiratory tract *** may be associated with hepatocellular involvement,as indicated by increased liver enzymes aspartate aminotransferase and alanine transaminase(ALT).AIm To evaluate the rate of increased liver enzyme levels in children with acute bronchiolitis and correlate them with clinical,laboratory,and radiological *** The study was a retrospective review of the medical records of children who presented with acute bronchiolitis when admitted to the Pediatric Department,Salmaniya medical Complex,the Kingdom of Bahrain,between 2019 and *** collected the demographic data,the clinical presentation,the laboratory and radiological findings,and the clinical *** compared the patients with elevated liver enzymes to those with normal levels at the time of presentation and at *** We included 166(57.8%)of 287 patients with acute bronchiolitis who fulfilled the inclusion ***-three(56%)patients were *** median age at presentation was 3.4(interquartile range 1.1 to 12.4)***-four(28%)patients tested positive for RSV,which was confirmed in 15 of them(28%)by *** findings of 161 patients tested at presentation showed high ALT levels in 14(8.7%)patients and normal ALT in 147(91.3%).Coagulation profiles were measured in 46(27.7%)of 166 *** prothrombin time was present in 15(32.6%),a high international normalized ratio was present in 13(28.3%),and high activated partial thromboplastin time was present in three(6.5%).Thrombin time was elevated in nine(27.3%)of 33 ***(21.7%)of 23 patients with available radiological data had hepatomegaly;one of them had findings suggestive of fatty *** ALT had a significant association with lengthy hospital stays(Pmented follow-up with liver function tests over a median follow-up period of

关键词： involvement elevated bronchiolitis

mechanism and technological evaluation of biopeptidal-based emulsions

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Food Bioscience 2022年第3期47卷 81-90页

作者： Tolulope Joshua Ashaolu Ramy m.Khoder mohammed saeed Alkaltham Asad Nawaz Noman Walayat muhammad Umair Ibrahim Khalifa Institute of Research and Development Duy Tan UniversityDa Nang550000Viet Nam Faculty of Environmental and Chemical Engineering Duy Tan UniversityDa Nang550000Viet Nam College of Food Science and Technology Huazhong Agricultural UniversityWuhanHubei Province430070PR China Department of Food Science & Nutrition College of Food and Agricultural SciencesKing Saud UniversityRiyadhSaudi Arabia Shenzhen Key Laboratory of marine microbiome Engineering Institute for Advanced StudyShenzhen UniversityShenzhen518060China College of Food Science and Technology Zhejiang University of TechnologyHangzhou310014China Department of Food Science and Engineering College of Chemistry and Environmental EngineeringShenzhen UniversityShenzhen518060GuangdongPR China Food Technology Department Faculty of Agriculture13736MoshtohorBenha UniversityEgypt

Both natural and synthetic peptides are not only biologically important,continuous research and comprehension of these short protein fragments show that they also have multifarious potentials in food manufacturing,namely emulsion-based *** emulsions may basically be oil-in-water or water-in-oil,as well as temporary,semi-permanent,or permanent in a continuous phase that suspends the droplets of the other elements used in food and pharmaceutical industries to formulate products such as gels,creams,ointments,and *** this review,the classification,preparation,and identification of peptides were described,followed by peptide-based emulsion properties and their relationship with regards to stability,structure,solubility,hydrophobicity,foaming,and water holding *** then dovetailed into the release rate and gastric stability of encapsulated peptides in the human digestive system,before exploring further needs and *** is desired that more studies be conducted to define the impact of carrier ingredients selection,encapsulation and processing techniques,environment,and peptides chemistry on peptide-based emulsions to attain high efficacy.

关键词： Peptides Emulsions Physicochemical properties Bioactivity Gastrointestinal stability

Effect of alumina content and heat treatment on microstructure and upconversion emission of Er^(3+)ions in oxyfluoride glass-ceramics

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Journal of Rare Earths 2012年第12期30卷 1228-1234页

作者： mohammad hasan Imanieh Bijan Eftekhari Yekta Vahak marghussian Inocencio Rafael martin Benenzuela Alberto Hernandez Creus saeed Shakhesi Esmaeil Eslami Department of materials Ceramic DivisionIran University of Science and Technology Nanotechnology Department Engineering Research Institute Department of Física Fundamental Electrónicay SistemasUniversity of La LagunaC.Astrofísico Francisco Sánchezs/n E-38206 La LagunaTenerifeSpain mALTA Consolider Team University of La LagunaC.Astrofísico Francisco Sánchezs/n E-38206 La LagunaTenerifeSpain Department of Química Física Instituto de Materialesy NanotecnologíaUniversity of La Laguna38205-La LagunaTenerifeSpain Nanotechnology Department Engineering Research Institute Tehran Department of Physics Iran University of Science and Technology (IUST)NarmakTehranIran

The effect of alumina content and heat treatment temperature and time, on microstructure and Er3＋（0.5 mol.%） emission of oxyfluoride glass-ceramics were investigated in this research. Two values of 1.8 （SA1.8Er0.5） and 2.18 （SA2.18Er0.5） were selected in this research for SiO2/Al2O3 ratio. According to DTA results, precursor glasses were heat treated at 630, 660 and 690 ℃ for 4 h and some glasses were also heat treated at 630 ℃ for 48 and 72 h. The results indicated that alumina content had significant effect on phase separation and viscosity of the glasses. Therefore the size, size distribution, and volume concentration of nano CaF2 crystals which precipitated during the heat treatment depended on alumina content of the glass. Due to the much smaller size of the precipitated CaF2 crystals in the glasses of low alumina content, these samples maintained excellent transparency and had narrower crystal size distribution than the high alumina glasses. The crystal size was increased markedly with the temperature increasing from 630 to 690 ℃. On the other hand a slight increase was observed in the crystal size by raising the heat treatment time in both glasses. Results indicated that in low alumina content glass （SA2.18Er0.5） the size of CaF2 nanocrystals was controlled in one order of magnitude. The increase of heat treatment time and temperature led to the incorporation of Er3＋ ions into CaF2 crystalline phase, increasing significantly the upconversion intensity. After heat treatment at 690 ℃for 4 h, atomic force microscope （AFm） revealed the development of small crystals with an average size of 80 and 30 nm in SA1.8Er0.5 and SA2.18Er0.5 samples, respectively.

关键词： oxyfluorides glass-ceramic CaF2 nanocrystals SiO3/Al2O3 ratio rare earths

Association of allergic rhinitis with hypothyroidism, asthma, and chronic sinusitis: clinical and radiological features

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World Journal of Otorhinolaryngology-Head and Neck Surgery 2022年第3期8卷 262-268页

作者： Aljuaid Eidha Fawzan Sara Ahmad Assiri Raad m.m.Althaqafi Atheer Alsufyani Ahmad saeed A.Alghamdi Otorhinolaryngology-Head and Neck Surgery Department Al-Hada Armed Forces Military HospitalTaifSaudi Arabia Taif University School of medicine TaifSaudi Arabia

Background: Allergic rhinitis (AR) is characterized by mucosal inflammation that leads to a variety of symptoms, such as nasal congestion, rhinorrhea, and sneezing. This rhinitis is triggered by inhalation of allergens, such as pollen, and this condition has a negative impact on the quality of life. AR was shown to be associated with a number of co-morbidities, including hypothyroidism, asthma, and chronic ***: This study aimed to assess AR-associated comorbidities in patients presenting symptoms and paranasal sinus computed tomography (CT) scan findings in Taif City, Saudi ***: This cross-sectional study evaluated medical and radiological records of AR patients retrospectively from the period of December 2018 to September 2019 in Al-Hada Armed Forces military Hospital, Taif City, Saudi ***: A total of 103 AR patients with a mean age of 39.0 ± 15.6 years with 55.3% males and 44.7% females. The three most common associated comorbidities in allergic rhinitis patients were chronic sinusitis (28.2%), hypothyroidism (21.4%), and asthma (8.7%). Nasal obstruction (30.1%) was the symptom most frequently presented by all patients. mucosal thickening occurred most frequently in patients with associated chronic sinusitis, while bilateral osteomeatal complex obliteration was observed mostly in asthmatic patients, and bony boundary thinning was more prevalent among patients with associated ***: The gender distribution of AR was 10% more common among males;however, the most common three comorbidites in allergic rhinitis patients were chronic sinusitis, hypothyroidism, and asthma, and most of those patients were females. Hypothyroidism can be a hidden predisposing factor for AR, while chronic sinusitis can be caused by AR due to secretion stasis or immune system activation.

关键词： Allergic Rhinitis Asthma Chronic Sinusitis CT scan Hypothyroidism Nasal obstruction Paranasal sinuses

Effect of size and indium-composition on linear and nonlinear optical absorption of InGaN/GaN lens-shaped quantum dot

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Chinese Physics B 2016年第5期25卷 380-387页

作者： Ahmed S Jbara Zulkafli Othaman m A saeed Center for Sustainable Nanomaterials Universiti Teknologi Malaysia Physics Department Science College Al-Muthanna University Department of Physics Faculty of Science Universiti Teknologi Malaysia

Based on the Schr ¨odinger equation for envelope function in the effective mass approximation, linear and nonlinear optical absorption coefficients in a multi-subband lens quantum dot are investigated. The effects of quantum dot size on the interband and intraband transitions energy are also analyzed. The finite element method is used to calculate the eigenvalues and eigenfunctions. Strain and In-mole-fraction effects are also studied, and the results reveal that with the decrease of the In-mole fraction, the amplitudes of linear and nonlinear absorption coefficients increase. The present computed results show that the absorption coefficients of transitions between the first excited states are stronger than those of the ground states. In addition, it has been found that the quantum dot size affects the amplitudes and peak positions of linear and nonlinear absorption coefficients while the incident optical intensity strongly affects the nonlinear absorption coefficients.

关键词： linear and nonlinear optical absorption coefficients lens quantum dot finite element method