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New coating formulation for the slow release of urea using a mixture of gypsum and dolomitic limestone

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Particuology 2015年第6期13卷 62-67页

作者： Farahnaz Eghbali Babadi robiah yunus Suraya Abdul Rashid Mohamad Amran Mohd Salleh Salmiaton Ali Institute of Advanced Technology Universiti Putra Malaysia Selangor 43400 Malaysia Departments of Chemical and Environmental Engineering Faculty of Engineering Universiti Putra Malaysia Selangor 43400 Malaysia

The use of urea and urea-based fertilizers has increased considerably over the past 15 years. They cur- rently account for approximately 51% of the world＇s agricultural nitrogen consumption. However, about 20-70% of the applied urea fertilizer is lost to the environment, causing serious pollution and increasing costs. These losses come from leaching, decomposition, and ammonium volatilization in the soil during handling and storage. Controlled release by coating can be used to increase urea fertilizer efficiency. We studied the use of gypsum, sulfur, and ground magnesium lime as cost-effective coating materials. All these coating materials contain nutrients required by plants. The effects of the coating composition and proportion of sealant on the rate of urea release and the crushing strength of the coated urea were investigated. We found that coated urea with the same proportion of gypsum-ground magnesium lime （GML） exhibited low urea release and high crushing strength. The performance was enhanced when using polyols as a sealant on the surface of the coated urea. A surface morphology analysis indicated a uniform and smooth surface on the coated film. The efficiency of the coated urea improved by 34.2% when using gypsum-GML （ 1：1 ratio） containing 1.1% oolvols.

关键词： Ground magnesium lime Crushing strength Rotary pan SealantPolyol

Assessing the kinetic model of hydro-distillation and chemical composition ofAquilaria malaccensis leaves essential oil

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Chinese Journal of Chemical Engineering 2017年第2期25卷 216-222页

作者： Mahtab Samadi Zurina Zainal Abidin robiah yunus Dayang Radiah Awang Biak Hiroyuki Yoshida Eng Hai Lok Department of Chemical and Environmental Engineering Faculty of EngineeringUniversity Putra MalaysiaserdangSelangorDaml Ehsan 43400Malaysia Aerospace Manufacturing Research Centre(AMRC) Level 7Tower BlockFaculty of EngineeringUniversity Putra Malaysia43400 5erdang SelangorMalaysia Forest Research Institute Malaysia 52109 Kepong5elangorDarul EhsanMalaysia

This study aimed to model the kinetic of hydro-distillation of Aquilaria malaccensis leaves oil in order to understand and optimize the extraction process. In addition, this study, for the first time, aimed to identify the chemical compositions of the A. rnalaccensis leave-oil. By assessing both first-order kinetic model and the model of simultaneous washing and diffusion, the result indicated that the model of simultaneous washing and diffusion better describes the hydro-distillation mechanism of the essential oil from A. rnalaccensis leaves. The optimum time, solid to liquid ratio, and the heating power for extracting the highest amount of essential oil were found to be around 3 h, 1：10 （g. ml-1）, and 300 W respectively. Yellow essential oil with a strong smell and a yield of 0.05 v/w was extracted by hydro-distillation Clevenger apparatus. Chemical compounds of the essential oil were analyzed using gas chromatography-mass spectroscopy （GC/MS）, which resulted in identification of 42 compounds that constitute 93% of essential oil. Among the identified components, Pentadecanal （32.082%）, 9-Octadecenal, （Z）（15.894%）, and Tetradecanal （6.927%） were the major compounds. Considering the fact that all the identified major components possess pesticidal properties, A. malaccensis leaves can be regarded as a promising natural source for producing pesticides.

关键词： Aquilaria malaccensisEssential oilHydro-distillationOptimizationKinetic modeling

Corrosion evaluation of friction stir welded lap joints of AA6061-T6 aluminum alloy

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Transactions of Nonferrous Metals Society of China 2016年第3期26卷 684-696页

作者： Farhad GHARAVI Khamirul A.MATORI robiah yunus Norinsan K.OTHMAN Firouz FADAEIFARD Materials Synthesis and Characterization Laboratory Institute of Advanced TechnologyUniversiti Putra Malaysia43400 UPM SerdangSelangorMalaysia Department of Physics Faculty of Science Universiti Putra Malaysia43400 UPM SerdangSelangorMalaysia Schools of Applied Physics Faculty of Science and Technology University Kebangsaan Malaysia43600 UPM BangiSelangorMalaysia

Corrosion behavior of friction stir lap welded AA6061-T6 aluminum alloy was investigated by immersion tests in sodium chloride + hydrogen peroxide solution. Electrochemical measurement by cyclic potentiodynamic polarization, scanning electron microscopy, and energy dispersive spectroscopy were employed to characterize corrosion morphology and to realize corrosion mechanism of weld regions as opposed to the parent alloy. The microstructure and shear strength of welded joint were fully investigated. The results indicate that, compared with the parent alloy, the weld regions are susceptible to intergranular and pitting attacks in the test solution during immersion time. The obtained results of lap shear testing disclose that tensile shear strength of the welds is 128 MPa which is more than 60% of the strength of parent alloy in lap shear testing. Electrochemical results show that the protection potentials of the WNZ and HAZ regions are more negative than the pitting potential. This means that the WNZ and HAZ regions do not show more tendencies to pitting corrosion. Corrosion resistance of parent alloy is higher than that for the weldments, and the lowest corrosion resistance is related to the heat affected zone. The pitting attacks originate from the edge of intermetallic particles as the cathode compared with the Al matrix due to their high self-corrosion potential. It is supposed that by increasing intermetallic particle distributed throughout the matrix of weld regions, the galvanic corrosion couples are increased, and hence decrease the corrosion resistance of weld regions.

关键词： friction stir welding lap joints AA6061 alloy pitting corrosion welding process intermetallic particles

Health awareness and lifestyle toward healthcare-seeking behavior among students in Universitas Advent Indonesia

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Frontiers of Nursing 2024年第3期11卷 337-342页

作者： Alvin Salim Natasha Ulima Sianturi Evi Martha Suryani yunus Elon Nursing Department Riau Andalan Pulp&PaperRiauIndonesia Faculty of Nursing Binawan UniversityJakartaIndonesia Nursing Department UNAI ClinicBandungIndonesia Faculty of Nursing Universitas Advent IndonesiaBandungIndonesia

Objective:Healthcare-seeking behavior(HSB)would affect the prevalence of morbidity and *** are various factors that affect one's *** study aimed to determine if health awareness and lifestyle might relate to ***:A cross-sectional study was applied by using three questionnaires to determine par ticipants'health awareness,lifestyle,and *** study took place in Universitas Advent Indonesia and the students were recruited to be par ***:There were 39 par ticipants joined in this *** of the par ticipants were females,third-year students,and from Accounting *** all participants were aware of their low risk of health issues,had a fine lifestyle,and had moderate ***:One's urge to seek health care facilities was not related to their health awareness and *** was no fur ther study to contradict with this finding at this moment.

关键词： health awareness healthcare-seeking behavior healthcare service utilization lifestyle public health

Production of Trimethylolpropane Ester Based Lubricant from Palm Oil

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材料科学与工程（中英文版） 2010年第11期4卷 13-18页

作者： Siti Zubaidah Sulaiman robiah yunus Luqman Chuah Abdullah Fakhru＇l-Razi Ahmadun Zulkafli Hassan Rohaida Che Man Faculty of Engineering Chemical and Natural Resources Universiti Malaysia Pahang Kuantan 25000 Pahang Malaysia Department of Chemical and Environmental Engineering Faculty of Engineering Universiti Putra Malaysia Serdang 43400 UPM Selangor Malaysia

Effect of Y addition on microstructure and corrosion behavior of extruded Mg-Zn-Nd-Zr alloy

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Journal of Magnesium and Alloys 2020年第3期8卷 640-653页

作者： Huseyin Zengin yunus Turen Department of Metallurgical and Materials Engineering Karabuk University78050 KarabukTurkey

In this study,the effect of Y addition(0,0.5,1 and 2 wt%)on microstructure and corrosion properties of Mg-6Zn-0.5Zr-1 Nd(wt%)alloy was *** alloys were produced by low-pressure die casting method and extruded at 300℃and 400℃after homogenization treatment at 400℃for 24 *** results showed that the as-cast microstructure of the alloy with no Y addition consisted ofα-Mg,Mg-Zn binary and Mg-Zn-Nd ternary *** increasing Y additions,the average grain size showed a substantial decrease and two kinds of ternary Mg-Zn-Y ternary phases,designated as I-phase(Mg3Zn6Y)and W-phase(Mg3Zn3Y2)were *** treatment resulted in a partial dissolution of second phase *** process gave rise to a remarkable grain refinement due to the DRX *** extruded alloys with no Y addition exhibited poor corrosion resistance due to the strong micro galvanic coupling effect.Y additions up to 1 wt%improved the corrosion resistance due to the formation of finer grains,fine and uniform distribution of second phase particles and more stable oxide film.

关键词： ZK60 magnesium alloys Rare earth Yttrium Extrusion Microstructure Corrosion

Grobner-Shirshov Basis of Twisted Generic Composition Algebras of Affine Type

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Algebra Colloquium 2017年第1期24卷 109-122页

作者： Gulshadam yunus Abdukadir Obul College of Mathematics and System Sciences Xinjiang University Urumqi 830046 China

In this paper, by using PBW bases for the twisted generic composition algebras of affine type, we prove that the set of the skew-commutator relations of the iso-classes of indecomposable representations forms a minima... 详细信息

关键词： Ringel-Hall algebra indecomposable modules Grobner-Shirshov basis skew-commutator relations

Grbner-Shirshov Basis of Quantum Group of Type D_4

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Chinese Annals of Mathematics,Series B 2011年第4期32卷 581-592页

作者： Gulshadam yunus Abdukadir OBUL College of Mathematics and System Sciences Xinjiang University

The authors take all isomorphism classes of indecomposable representations as new generators, and obtain all skew-commutators between these generators by using the Ringel-Hall algebra method. Then they prove that the ... 详细信息

关键词： Ringel-Hall algebra Indecomposable modules GrSbner-Shirshov basis Compositions

Effect of surfactant on the dielectric and electrorheological properties of zinc borate/silicone oil dispersions

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International Journal of Minerals,Metallurgy and Materials 2019年第12期26卷 1523-1530页

作者： Omer yunus Gumus Halil Ibrahim Unal Bursa Technical University Engineering and Natural Sciences FacultyFiber and Polymer Engineering DepartmentBursa 16310Turkey Gazi University Science FacultyChemistry DepartmentSmart Materials Research Lab.Ankara 06500Turkey

Zinc borate(ZB)particles dispersed in silicone oil(SO)at concentrations of φ=5vol%-20vol% were subjected to dielectric analysis to elucidate their polarization strength,time,and *** revealed that all virgin dispersions lacked *** X-100,a non-ionic surfactant,was added to ZB/SO dispersions to enhance the polarizability of ZB *** addition of 1vol% Triton X-100 enhanced the polarizability of ZB/SO dispersions,and the 15vol% ZB/SO system provided the highest dielectric difference Δε′(the difference in ε′values at zero and infinite frequency,Δε′=ε0–ε∝)of *** electrorheological(ER)activities of the ZB/SO/Triton-X dispersion system were determined through the ER response test,and viscoelastic behaviors were investigated via oscillation tests.A recoverable deformation of 36% under an applied electrical field strength of 1.5 kV/mm was detected through creep and creep recovery tests.

关键词： zinc borate electrorheological fluids dielectric analysis surfactant