The relations between null geodesic curves and timelike ruled surfaces in dual Lorentzian space $\mathbb{D}_{1}^{3}$

Yasin \"{U}nl\"{u}t\"{u}rk,S\"{u}ha Y\i lmaz,Cumali Ekici 호남수학회 2019 호남수학학술지 Vol.41 No.1

In this work, we study the conditions between null geodesic curves and timelike ruled surfaces in dual Lorentzian space. For this study, we establish a system of differential equations characterizing timelike ruled surfaces in dual Lorentzian space by using the invariant quantities of null geodesic curves on the given ruled surfaces. We obtain the solutions of these systems for special cases. Regarding to these special solutions, we give some results of the relations between null geodesic curves and timelike ruled surfaces in dual Lorentzian space.

Decreased Prolidase Activity in Patients with Posttraumatic Stress Disorder

Süleyman Demir,Mahmut Bulut,Abdullah Atli,I·brahim Kaplan,Mehmet Cemal Kaya,Yasin Bez,Pınar Güzel Özdemir,Aytekin Sır 대한신경정신의학회 2016 PSYCHIATRY INVESTIGATION Vol.13 No.4

ObjectiveaaMany neurochemical systems have been implicated in the development of Posttraumatic Stress Disorder (PTSD). The prolidase enzyme is a cytosolic exopeptidase that detaches proline or hydroxyproline from the carboxyl terminal position of dipeptides. Prolidase has important biological effects, and to date, its role in the etiology of PTSD has not been studied. In the present study, we aimed to evaluate prolidase activity in patients with PTSD. MethodsaaThe study group consisted of patients who were diagnosed with PTSD after the earthquake that occurred in the province of Van in Turkey in 2011 (n=25); the first control group consisted of patients who experienced the earthquake but did not show PTSD symptoms (n=26) and the second control group consisted of patients who have never been exposed to a traumatic event (n=25). Prolidase activities in the patients and the control groups were determined by the ELISA method using commercial kits. ResultsaaProlidase activity in the patient group was significantly lower when compared to the control groups. Prolidase activity was also significantly lower in the traumatized healthy subjects compared to the other healthy group (p<0.01). ConclusionaaThe findings of the present study suggest that the decrease in prolidase activity may have neuroprotective effects in patients with PTSD.

Onset of Magnetic Order in U2(Ni1−xFex)2Sn-H

S. Maˇskov´a,L. Havela,A. Kolomiets,K. Miliyanchuk,A. V. Andreev,H. Nakotte,J. Peterson,Y. Skourski,S. Yasin,S. Zherlitsyn,J. Wosnitza 한국물리학회 2013 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.62 No.10

We present specific heat and magnetic studies as a function of temperature and magnetic field for U2(Ni1−xFex)2Sn alloys (x = 0.0, 0.05, 0.1, 0.15, 0.2, 0.4, 0.6 and 0.8) and their hydrides (absorption of ≈ 2 H/f.u.). For the parent alloys, antiferromagnetic order is rapidly suppressed with increasing Fe concentration and non-Fermi-liquid behavior was found for x = 0.2. Hydrogenation of the parent alloys causes a substantial increase of TN in Fe-low hydrides (x < 0.2), while Fe-rich hydrides show an unexpected appearance of ferromagnetism in the range 0.4 ≤ x ≤ 0.8. Some of the findings are compared with similar studies in U2Co2Sn and U2Co2InH1.9.

Design of novel electrode for capacitive deionization using electrospun composite titania/zirconia nanofibers doped-activated carbon

Yasin, Ahmed S.,Mohamed, Ibrahim M.A.,Park, Chan Hee,Kim, Cheol Sang Elsevier 2018 Materials letters Vol.213 No.-

<P><B>Abstract</B></P> <P>Well-dispersed TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> nanofibers-doped activated carbon (AC/TiZr) were successfully synthesized as an electrode for the capacitive deionization (CDI) technique via electrospinning that was followed by a hydrothermal treatment. SEM, TEM, XRD, XPS and EDX measurements were employed to characterize the morphology, crystal structure and chemistry composition of the as-synthesized material. The electrochemical performance of the AC/TiZr nanocomposite modified electrode was measured using systematic cyclic voltammetry (CV) experiments. The highest specific capacitance for the AC/TiZr-based electrode is 251.3 Fg/g, which is higher than those of the AC (207.4 Fg/g) and TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> NFs (0.4 Fg/g)-based electrodes, and the interior resistance was also reduced. A desalination performance enhancement was obtained in the case of the AC/TiZr and the electrosorptive is 2.96 mg g<SUP>−1</SUP>. The implementation of the AC/TiZr nanocomposite provided a high potential for improving the efficiency of CDI.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effective TiO<SUB>2</SUB>/ZrO<SUB>2</SUB> NFs incorporated AC are introduced for CDI. </LI> <LI> Improvement in wettability (16.9°) is due to modifying the carbon-based electrode. </LI> <LI> Low inner resistance and high specific capacitance are observed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effect of internal pressure and gas/liquid interface area on the CO mass transfer coefficient using hollow fibre membranes as a high mass transfer gas diffusing system for microbial syngas fermentation

Yasin, M.,Park, S.,Jeong, Y.,Lee, E.Y.,Lee, J.,Chang, I.S. Elsevier Applied Science 2014 Bioresource technology Vol.169 No.-

This study proposed a submerged hollow fibre membrane bioreactor (HFMBR) system capable of achieving high carbon monoxide (CO) mass transfer for applications in microbial synthesis gas conversion systems. Hydrophobic polyvinylidene fluoride (PVDF) membrane fibres were used to fabricate a membrane module, which was used for pressurising CO in water phase. Pressure through the hollow fibre lumen (P) and membrane surface area per unit working volume of the liquid (A<SUB>S</SUB>/V<SUB>L</SUB>) were used as controllable parameters to determine gas-liquid volumetric mass transfer coefficient (k<SUB>L</SUB>a) values. We found a k<SUB>L</SUB>a of 135.72h<SUP>-1</SUP> when P was 93.76kPa and A<SUB>S</SUB>/V<SUB>L</SUB> was fixed at 27.5m<SUP>-1</SUP>. A higher k<SUB>L</SUB>a of 155.16h<SUP>-1</SUP> was achieved by increasing A<SUB>S</SUB>/V<SUB>L</SUB> to 62.5m<SUP>-1</SUP> at a lower P of 37.23kPa. Practicality of HFMBR to support microbial growth and organic product formation was assessed by CO/CO<SUB>2</SUB> fermentation using Eubacterium limosum KIST612.

Theoretical insight into the structure-property relationship of mixed transition metal oxides nanofibers doped in activated carbon and 3D graphene for capacitive deionization

Yasin, Ahmed S.,Mohamed, Ahmed Yousef,Mohamed, Ibrahim M.A.,Cho, Deok-Yong,Park, Chan Hee,Kim, Cheol Sang Elsevier 2019 CHEMICAL ENGINEERING JOURNAL -LAUSANNE- Vol.371 No.-

<P><B>Abstract</B></P> <P>Over the last two decades, the capacitive deionization (CDI) technique has been developed into a high performance, low-cost, and environmental-friendly desalination technology. The development of novel advanced nanostructures via the hybridization of diverse carbon materials to improve the performance of CDI technology has attracted considerable attention. In this study, the combination of graphene hydrogel and ZrO<SUB>2</SUB>-doped TiO<SUB>2</SUB> nanofibers as efficient dopants into activated carbon (AC), has been achieved through a simple electrospinning technique followed by a post annealing process. The strong interactions between the graphene hydrogel, nanofibers and AC were found to enhance the wettability as well as the electrical conductivity of the AC. The morphology and electrochemical performance of the as-synthesized composite were characterized by field-emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). What’s more, the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and synchrotron X-ray absorption structures (XAS) are performed to investigate the atomic and electronic structure of titania and zirconia in order to understand their phase stability. We observed the appearance of anatase structure of titania and cubic structure of zirconia after doping the AC and graphene hydrogel with the nanofibers. The water contact angle of the composite was examined and found to be less than 3°. The introduced nanocomposite showed high electrosorption capacity of 9.34 mg g<SUP>−1</SUP> at the initial solution conductivity of ∼100 μS cm<SUP>−1</SUP>, which is much higher compared to the other surveyed materials; these results should be attributed to its significant hydrophilicity, high specific capacitance, and reduced charge transfer resistance.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Unique three-dimensional graphene/mixed transition metal oxides modified activated carbon was prepared and characterized. </LI> <LI> The nanocomposite electrode shows low charge transfer resistance and high specific capacitance. </LI> <LI> Analysis of synchrotron-based hard X-ray absorption spectroscopy. </LI> <LI> The fabricated nanocomposite exhibits a high electrosorption capacity of 9.34 mg g<SUP>−1</SUP>. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Incorporating zirconia nanoparticles into activated carbon as electrode material for capacitive deionization

Yasin, Ahmed S.,Mohamed, Ibrahim M.A.,Amen, Mohamed T.,Barakat, Nasser A.M.,Park, Chan Hee,Kim, Cheol Sang Elsevier 2019 Journal of alloys and compounds Vol.772 No.-

<P><B>Abstract</B></P> <P>In recent years, capacitive deionization (CDI) has attracted intensive research due to its environmentally-friendly nature and low power requirement. Although the characteristics of titania (TiO<SUB>2</SUB>) and zirconia (ZrO<SUB>2</SUB>) are almost the same, ZrO<SUB>2</SUB> has not attracted the same attention since the characteristics of the carbonaceous material need to be modified to enhance its performance as an electrode in CDI cells. In this study, the wettability and electrochemical behavior of activated carbon (AC), as a widely used, effective, and inexpensive material, was distinctively improved by doping with zirconia nanoparticles. The introduced AC/ZrO<SUB>2</SUB> nanocomposite was fabricated using the alkaline hydrothermal method. Investigation of the surface morphology, phase and crystallinity by SEM, TEM, XPS, and XRD demonstrated the successful doping of AC by zirconia nanoparticles. Interestingly, the wettability measurement showed excellent enhancement, since the water contact angles of pristine and doped AC are 45° and 148°, respectively. The electrochemical experiments demonstrated that the synthesized composite (AC/ZrO<SUB>2</SUB>) has a specific capacitance of 282.8 F g<SUP>−1</SUP>, which is higher than that for AC (207.5 F g<SUP>−1</SUP>). Due to the significant improvement in wettability and specific capacitance, the desalination performance and the salt ion electrosorption capacity were also enhanced: 40.4% and 68.5%, and 2.82 and 4.79 mg/g for AC and AC/ZrO<SUB>2</SUB>, respectively. Moreover, the introduced AC/ZrO<SUB>2</SUB> revealed 99% remaining desalination retention suggesting high stability. Overall, this study demonstrates ZrO<SUB>2</SUB> is an effective, stable, and environmentally safe material for improving the performance of carbonaceous CDI electrodes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> ZrO<SUB>2</SUB> NPs/AC is introduced as effective CDI electrode material. </LI> <LI> The salt removal efficiency has been improved to 68.5%. </LI> <LI> Good performance is due to improving the specific capacitance. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Fabrication of N-doped &SnO₂-incorporated activated carbon to enhance desalination and bio-decontamination performance for capacitive deionization

Yasin, Ahmed S.,Jeong, Jongku,Mohamed, Ibrahim M.A.,Park, Chan Hee,Kim, Cheol Sang Elsevier 2017 JOURNAL OF ALLOYS AND COMPOUNDS Vol.729 No.-

<P><B>Abstract</B></P> <P>Herein, nitrogen-doped tin oxide intercalated activated carbon nanocomposite (N-AC/SnO<SUB>2</SUB>) were prepared using hydrothermal strategy and explored as an electrode for capacitive desalination and disinfection. Although tin oxide (SnO<SUB>2</SUB>) has good characteristics, the nitrogen must be carefully considered for modifying the characteristics of the carbonaceous materials to improve the performance as an electrode in the CDI process. The characterization of the proposed materials which investigated by XRD, TEM, FE-SEM, XPS and FT-IR affirmed the formation of the nanocomposite. The electrosorption behavior investigated by electrochemical techniques demonstrates that, compared to the specific capacitance of the AC and AC/SnO<SUB>2</SUB> (207.46 F g<SUP>−1</SUP> and 233.21 F g<SUP>−1</SUP>), that of the N-AC/SnO<SUB>2</SUB> is higher at 408.8 F g<SUP>−1</SUP>, and N-AC/SnO<SUB>2</SUB> exhibits better electrical conductivity. The CDI performance evaluated by batch mode experiments through an applied voltage of 1.2 V in a 50 mg L<SUP>−1</SUP> NaCl aqueous solution shows that the N-AC/SnO<SUB>2</SUB> electrode introduces a higher electrosorptive capacity of 3.42 mg g<SUP>−1</SUP>, an enhanced desalination efficiency of 61.13%, and good antibacterial performance. Overall, the present study demonstrates that N-AC/SnO<SUB>2</SUB> has considerable potential as an electrode material for CDI application.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Nitrogen-doped SnO<SUB>2</SUB> intercalated AC is introduced as novel CDI electrode material. </LI> <LI> The desalination behavior has been improved to be 61.13%. </LI> <LI> Good bio-decontamination performance is attributed to modifying the carbon-based electrode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Enhanced desalination performance of capacitive deionization using zirconium oxide nanoparticles-doped graphene oxide as a novel and effective electrode

Yasin, A.S.,Mohamed, H.O.,Mohamed, I.M.A.,Mousa, H.M.,Barakat, N.A.M. Elsevier Science B.V 2016 Separation and purification technology Vol.171 No.-

Due to its eco-friendly and low energy technique for removing salt ions from saline water, capacitive deionization (CDI) is highly recommended as a desalination process. Based on its good features, large surface area and good electric conductivity, graphene oxide is a promising electrode in the CDI technology if the specific capacitance could be enhanced. In this study, to improve the electrochemical performances, novel ZrO<SUB>2</SUB> nanoparticles-incorporated graphene oxide nanosheets with different concentrations were successfully synthesized by hydrothermal treatment, their electrosorption characteristics in CDI unit were examined. The morphology, structure and electrochemical performance of the fabricated materials were investigated by scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), cyclic voltammetry and electrochemical impedance spectroscopy. The capacitive and electrosorption performances in NaCl solution were studied. Moreover, the role of ZrO<SUB>2</SUB> loading was investigated. The introduced ZrO<SUB>2</SUB>-doped graphene oxide showed a distinct improvement in the electrosorption capacity and revealed higher specific capacitance compared to the pristine graphene oxide. The obtained results indicated that the synthesized ZrO<SUB>2</SUB>-doped graphene oxide nanocomposite having 10wt.% ZrO<SUB>2</SUB> displayed a significant increase in the specific capacitance as the corresponding value (452.06F/g) was nine folds more than that of the pristine GO at 10mV/s. Moreover, the same electrode exhibits great cycling stability, excellent salt removal efficiency (93.03%), and distinct electrosorptive capacity (4.55mg/g). Overall, the proposed GO/ZrO<SUB>2</SUB> nanoparticle composite electrode is appropriate for utilizing as optimum electrodes for the CDI technique.

Exact third-order static and free vibration analyses of functionally graded porous curved beam

Mirza S. Beg,Hasan M. Khalid,Mohd Y. Yasin,L. Hadji 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.39 No.1

An exact solution based on refined third-order theory (TOT) has been presented for functionally graded porous curved beams having deep curvature. The displacement field of the refined TOT is derived by imposing the shear free conditions at the outer and inner surfaces of curved beams. The properties of the two phase composite are tailored according the power law rule and the effective properties are computed using Mori-Tanaka homogenization scheme. The equations of motion as well as consistent boundary conditions are derived using the Hamilton's principle. The curved beam stiffness coefficients (A, B, D) are obtained numerically using six-point Gauss integration scheme without compromising the accuracy due to deepness (1+z/R) terms. The porosity has been modeled assuming symmetric (even) as well as asymmetric (uneven) distributions across the cross section of curved beam. The programming has been performed in MATLAB and is validated with the results available in the literature as well as 2D finite element model developed in ABAQUS. The effect of inclusion of 1+z/R terms is studied for deflection, stresses and natural frequencies for FG curved beams of different radii of curvature. Results presented in this work will be useful for comparison of future studies.