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      • KCI등재

        Morphology controlled facile synthesis of MnO2 adsorbents for rapid strontium removal

        Umar Asim,Syed M. Husnain,Naseem Abbas,Faisal Shahzad,Abdul Rehman Khan,Tahir Ali 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.98 No.-

        MnO2 nanostructures with three distinct architectures, namelyflower, balk and tube-like, have beensynthesized through a single step microwave assisted hydrothermal method at different reactiontemperatures (110 C, 140 C and 180 C). The characterization of as prepared MnO2 samples wereperformed by means of Fourier transform infrared spectroscopy, X-ray diffraction, scanning electronmicroscopy, and transmission electron microscopy. The N2 adsorption–desorption isotherms revealedthe higher specific surface area and porosity of theflower like MnO2 as compared to balk and tube-likeMnO2. The adsorption behavior of as prepared adsorbents was investigated towards Sr2+ radionuclide. Because of the hierarchal structure and the high surface area (62.64 m2/g), MnO2-110 depicted the bestSr2+ adsorption performance with maximum adsorption capacity of 52 mg/g at pH 6 as compared to otherMnO2 morphologies synthesized at 140 C and 180 C. The kinetic studies revealed that the adsorption ofSr2+ onto MnO2-110 followed the pseudo-first-order model whereas the adsorption equilibrium dataobeyed the Freundlich and Sips model. Moreover, the MnO2-110 adsorbent reached the steady statequickly ( 10 min) and is capable to bind Sr2+ in slightly acidic to alkaline solutions.

      • SCIESCOPUSKCI등재

        Physicochemical Properties of Gelatin Extracted from Buffalo Hide Pretreated with Different Acids

        Mulyani, Sri,Setyabudi, Francis.M.C. Sigit,Pranoto, Yudi,Santoso, Umar Korean Society for Food Science of Animal Resource 2017 한국축산식품학회지 Vol.37 No.5

        The acid pretreatment of collagen molecules disrupts their crosslinks and assists in the release of acid-soluble proteins, fats, and other components. Generally, to achieve optimum extraction efficiency, strong acids may be used at a lower acid concentration compared to weak acids. This study aimed to determine the yield and physicochemical properties of gelatins extracted from buffalo hides pretreated with different acids. Hides were extracted with hydrochloric, citric, and acetic acids at concentrations of 0.3, 0.6, 0.9, 1.2, and 1.5 M. A completely randomized design and the least significant difference test were used in the experimental design, and all measurements were performed in triplicate. The highest yield (29.17%) was obtained from pretreatment with 0.9 M HCl. The gel strength did not differ significantly (p>0.05) according to acid type (280.26-259.62 g Bloom), and the highest viscosity was obtained from the 0.6 M citric acid pretreatment. All the gelatins contained ${\alpha}$- and ${\beta}$-chain components and several degraded peptides (24-66 kDa). The color and Fourier-transform infrared spectrum of the gelatin extracted using 0.9 M HCl were similar to those of commercial bovine skin gelatin. In general, the physicochemical properties of the gelatin complied with the industry standard set by the Gelatin Manufacturers Institute of America, revealing that buffalo hide could serve as a potential alternative source of gelatin.

      • KCI등재

        Physicochemical Properties of Gelatin Extracted from Buffalo Hide Pretreated with Different Acids

        Sri Mulyani,Francis.M.C,Sigit Setyabudi,Yudi Pranoto,Umar Santoso 한국축산식품학회 2017 한국축산식품학회지 Vol.37 No.5

        '스콜라' 이용 시 소속기관이 구독 중이 아닌 경우, 오후 4시부터 익일 오전 9시까지 원문보기가 가능합니다.

        The acid pretreatment of collagen molecules disrupts their crosslinks and assists in the release of acid-soluble proteins, fats, and other components. Generally, to achieve optimum extraction efficiency, strong acids may be used at a lower acid concentration compared to weak acids. This study aimed to determine the yield and physicochemical properties of gelatins extracted from buffalo hides pretreated with different acids. Hides were extracted with hydrochloric, citric, and acetic acids at concentrations of 0.3, 0.6, 0.9, 1.2, and 1.5 M. A completely randomized design and the least significant difference test were used in the experimental design, and all measurements were performed in triplicate. The highest yield (29.17%) was obtained from pretreatment with 0.9 M HCl. The gel strength did not differ significantly (p>0.05) according to acid type (280.26-259.62 g Bloom), and the highest viscosity was obtained from the 0.6 M citric acid pretreatment. All the gelatins contained α- and β-chain components and several degraded peptides (24-66 kDa). The color and Fourier-transform infrared spectrum of the gelatin extracted using 0.9 M HCl were similar to those of commercial bovine skin gelatin. In general, the physicochemical properties of the gelatin complied with the industry standard set by the Gelatin Manufacturers Institute of America, revealing that buffalo hide could serve as a potential alternative source of gelatin.

      • SCISCIESCOPUS

        ZnO Nanorods Based Hydrazine Sensors

        Umar, Ahmad,Rahman, M. M.,Hahn, Yoon-Bong American Scientific Publishers 2009 Journal of nanoscience and nanotechnology Vol.9 No.8

        <P>Electrochemical sensor for the detection of hydrazine has been fabricated at the surface of gold electrode modified with ZnO nanorods. The ZnO nanorods were grown by non-catalytic simple thermal evaporation process by using metallic zinc powder in the presence of oxygen at low-temperature. The detailed structural studies revealed that the as-grown ZnO nanorods are well-crystalline with the wurtzite hexagonal phase and grown along the [0001] direction in preference. A good and reproducible sensitivity of 4.76 microA cm(-2) microM(-1) has been obtained from the fabricated hexagonal-shaped ZnO nanorods based electrochemical sensor. The response time of the fabricated sensor was less than 10 s with a linear range from 0.2 to 2.0 microM and correlation coefficient of R = 0.9914. The limit of detection (LOD), based on S/N ratio was estimated to be 2.2 microM.</P>

      • SCISCIESCOPUS

        ZnO Nanonails: Synthesis and Their Application as Glucose Biosensor

        Umar, Ahmad,Rahman, M. M.,Kim, S. H.,Hahn, Y. B. American Scientific Publishers 2008 Journal of nanoscience and nanotechnology Vol.8 No.6

        <P>Well-crystallized zinc oxide nanonails were grown in a high density by thermal evaporation process and were used as supporting matrixes for glucose oxidase (GOx) immobilization to construct efficient glucose biosensor. The GOx attached to the surfaces of ZnO nanonails had more spatial freedom in its orientation, which facilitated the direct electron transfer between the active sites of immobilized GOx and electrode surface. The fabricated biosensor showed a high sensitivity of 24.613 <I>μ</I>A cm<SUP>-2</SUP> mM<SUP>-1</SUP> with a response time less than 10 s. Moreover, it shows a linear range from 0.1 to 7.1 mM with a correlation coefficient of R = 0.9937 and detection limit of 5 <I>μ</I>M.</P>

      • Manipulation of Magnetic State in Armchair Black Phosphorene Nanoribbon by Charge Doping

        Farooq, M. Umar,Hashmi, Arqum,Hong, Jisang American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.26

        <P>Using first-principles studies, we investigated the width-dependent magnetic properties of armchair black phosphorene nanoribbons (APNRs) by controlling the electron charge doping. In the unrelaxed APNRs the antiferromagnetic coupling between two phosphorus atoms in the same edge was found. However, the edge magnetic moment vanished after structure relaxation, and all of the APNRs showed a semiconducting feature. Interestingly, the charge doping substantially altered the band structures of the APNRs because the metallic states reappeared in the charge-doped APNRs. Besides this, the magnetic moment was found in the charge-doped systems. We found that the Stoner condition could nicely explain the magnetic moment at the edge atoms. Moreover, we propose that the edge-to-edge magnetic coupling can be manipulated by charge doping because the transition from the antiferromagnetic to ferromagnetic state was achieved. Our findings may bring interesting issues for spintronics applications.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-26/acsami.5b03284/production/images/medium/am-2015-03284j_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b03284'>ACS Electronic Supporting Info</A></P>

      • KCI등재

        IMPACT BEHAVIOR MODELING OF MOTORCYCLE FRONT WHEEL-TIRE ASSEMBLY

        K. S. TAN,S. V. WONG,R. S. RADIN UMAR,N. K. GUPTA,A. M. S. HAMOUDA 한국자동차공학회 2009 International journal of automotive technology Vol.10 No.3

        Experiments were conducted to investigate the influence of certain parameters that affect the impact response of the motorcycle front wheel-tire assembly under various impact conditions. Impact tests were conducted according to 2V 5–1 fractional factorial design using a pendulum impact test apparatus with impact speed, impact mass, tire inflation pressure level, striker geometry, and impact location as design factors. Significant factors influencing the response of the wheel-tire assembly were identified. Coefficients for each factor were also determined, and empirical models were then developed for each response. An analysis indicates that the developed models fit well within the experimental ranges of the respective factors. However, for several interaction effects, the models become unrealistic, whereby they give certain deformation values when approaching zero impact mass and/or zero impact velocity. This is not consistent with the mechanics of the physical world, as there should not be any significant deformation when delivered impact energy is small enough. Efforts have been made in developing better models to resolve the inconsistency and to include a wider range, especially considering the case of the lower limit of experimental factors, which are an impact mass of 51.18 kg and/or an impact velocity of 3 m s−1 (10.8 km/h) down to zero. The minimum amount of impact energy required to produce the onset of observable deformation on the wheel was incorporated in the development of new models. Finally, the present models have been developed not only to cover the lower regions but also to range up to the upper limits of the factors, which are an impact mass of 101.33 kg and an impact velocity of 6 m s−1 (21.6 km/h). Experiments were conducted to investigate the influence of certain parameters that affect the impact response of the motorcycle front wheel-tire assembly under various impact conditions. Impact tests were conducted according to 2V 5–1 fractional factorial design using a pendulum impact test apparatus with impact speed, impact mass, tire inflation pressure level, striker geometry, and impact location as design factors. Significant factors influencing the response of the wheel-tire assembly were identified. Coefficients for each factor were also determined, and empirical models were then developed for each response. An analysis indicates that the developed models fit well within the experimental ranges of the respective factors. However, for several interaction effects, the models become unrealistic, whereby they give certain deformation values when approaching zero impact mass and/or zero impact velocity. This is not consistent with the mechanics of the physical world, as there should not be any significant deformation when delivered impact energy is small enough. Efforts have been made in developing better models to resolve the inconsistency and to include a wider range, especially considering the case of the lower limit of experimental factors, which are an impact mass of 51.18 kg and/or an impact velocity of 3 m s−1 (10.8 km/h) down to zero. The minimum amount of impact energy required to produce the onset of observable deformation on the wheel was incorporated in the development of new models. Finally, the present models have been developed not only to cover the lower regions but also to range up to the upper limits of the factors, which are an impact mass of 101.33 kg and an impact velocity of 6 m s−1 (21.6 km/h).

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