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Radio-frequency Shot-noise Measurement in a Magnetic Tunnel Junction with a MgO Barrier
Mushtaq Rehman,박정환,송운,이연섭,민병철,신경호,류상완,김정구,정연욱 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.4
We measured the noise power of a magnetic tunnel junction in the frequency range of 710 1200 MHz. A low-noise cryogenic HEMT amplifier was used to measure the small noise signal at a high frequency with wide bandwidth. The MgO-barrier tunnel junction showed large tunnel magnetoresistance ratio of 215% at low temperature, which indicates electronic transport through the tunnel barrier without any significant spin-flip scattering. In the bias-dependent noise measurement, however, the zero-bias shot noise was enhanced compared to the value expected from a perfect tunnel barrier or the value observed from a good Al-AlOx-Al tunnel junction. We assume that this enhanced noise comes from inelastic tunneling processes through the barrier, which may be related to the observed zero-bias anomaly in the differential resistance of the tunnel junctions. We present a simple phenomenological model for how the inelastic scattering process can enhance the zero-bias noise in a tunnel junction.
Mushtaq, Azeem,Cho, Hoon,Ahmed, Muhammad Ajaz,Rehman, Muhammad Saif Ur,Han, Jong-In Elsevier 2019 Journal of membrane science Vol.590 No.-
<P><B>Abstract</B></P> <P>In this study, a new method of fabricating highly electro-conductive membranes, namely electroplating, was developed and its product performance was examined via microalgae harvesting. In this method, a layer of silver nanowires (AgNWs) was first vacuum-deposited on a poly(ether sulfone) support, followed by electroplating of silver layer. The electroplated membrane (C-AgNWs) found to exhibit surpassingly enhanced electrical conductivity (3.9 × 10<SUP>4</SUP> S/cm) and a satisfactory level of mechanical stability under prolonged filtration. When microalgae, <I>Chlorella</I> sp. HS-2, was harvested via electro-filtration, the membrane exhibited the intended effect of fouling mitigation, both in continuous and intermittent electric fields. This was attributed to the enhanced electrostatic repulsive forces between foulants and membrane along with in-situ electro-bubble generation from the membrane, reducing the overall blockage of the membrane surface. The intermittent mode was able to effectively mitigate fouling and recover flux to its initial level, with the effect compromised in successive steps. The continuous mode, however, did not display such performance degradation over time, but an increase of 480% in permeate flux at 20 V/mm. All this supported that the electroplating can serve as a promising route for the sake of fabricating the workable electro-membranes, conductive membranes that have boundless application potentials.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Electroplating can be a useful method for workable electro-membrane fabrication. </LI> <LI> Highly electro-conductive (3.9 × 10<SUP>4</SUP> S/cm) yet stable electro-membrane can be synthesized by this method. </LI> <LI> The AgNWs-based electroplated membrane can be used for efficient microalgae harvesting. </LI> <LI> The fabricated membrane can exhibit good antifouling property in continuous and intermittent modes of electro-filtration. </LI> </UL> </P>
Transmission Properties of Cryogenic Twisted Pair Filters
송운,Mushtaq Rehman,류상완,정연욱 한국물리학회 2010 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.57 No.6
We fabricated a cryogenic low pass filter that consists of twisted pairs of manganin wires wrapped in copper tape and measured its transmission characteristics at frequencies up to 18 GHz. The dependence of the microwave transmission characteristics on the filter length was studied, which showed that a filter of length 1.0 m had a 70-dB attenuation at 1 GHz. We also studied the dependence of common- and differential-mode transmission on the number of twists per unit length and found that the number of twists per unit length affects differential-mode transmission but not common-mode transmission. Because the shielded twisted pair filter is more compact than a conventional copper powder filter, it can solve the space and thermal load issues when many cables are required for precision electronic transport experiments at low temperatures.
Firoz Anwar,Rajbala Singh,Gohar Mushtaq,Abdul Rehman Al-Maliki,Abdullah Sabih,F. A. Al-Abbasi,Aftab Ahmad,Muhammad Afzal,Imran Kazm,Ruqaiyah Kha 대한독성 유전단백체 학회 2015 Molecular & cellular toxicology Vol.11 No.3
Hepatocellular carcinoma (HCC) is the fifth and third most common cause of cancer-related deaths. Erythrosine, a commonly used coloring agent in tablet preparation was studied for its role when supplemented with sub necrotic dose of DENA (n-diethyl nitrosamine) to induced HCC in Wistar rats. Single dose of chemical carcinogen DENA with intraperitoneal injection (20 mg/kg) administered before Erythrosine at a dose 0.014 mg/kg by p.o, DENA treated rats and alone. Exposure of DENA and Erythrosine alters the levels of Serum glutamate oxaloacetate transaminase (SGO T), Serum glutamate pyrophosphate transaminase (SGPT), Alkaline phosphate (ALP), Total Bilirubin (TBR), Blood uric acid, urea, lipid profile and Serum alpha-feto protein (AFP) in Wistar rats, with further alteration in intracellular antioxidant enzyme profile Lipid Per oxidation (LPO), Glutathione Peroxidase (GPx), Melanoaldehyde (MDA), Glutathione Reductase (GR), Catalase (CAT), Glutathione (GSH), Glutathione- S-Transferase (GST), Superoxide Dismutase (SOD) along with Vit. C and Vit. E conc.. Moreover Histopathological examinations of the liver tissue showed marked effect of DENA and Erythrosine exposure on liver structure. The results concluded that Erythrosine used as coloring agent for tablet coating as well as food colorant in India, was found to be an inducer as liver proliferating agent and promoter of HCC.
Ahmed Ammar,Azam Ali,Wang Yanen,Zhang Zutao,Li Ning,Jia Changyuan,Mushtaq Ray Tahir,Rehman Mudassar,Gueye Thierno,Shahid Muhammad Bilal,Basit Ali Wajid 나노기술연구협의회 2021 Nano Convergence Vol.8 No.37
Additively manufactured nano-MEH systems are widely used to harvest energy from renewable and sustainable energy sources such as wind, ocean, sunlight, raindrops, and ambient vibrations. A comprehensive study focusing on in-depth technology evolution, applications, problems, and future trends of specifically 3D printed nano-MEH systems with an energy point of view is rarely conducted. Therefore, this paper looks into the state-of-the-art technologies, energy harvesting sources/methods, performance, implementations, emerging applications, potential challenges, and future perspectives of additively manufactured nano-mechanical energy harvesting (3DP-NMEH) systems. The prevailing challenges concerning renewable energy harvesting capacities, optimal energy scavenging, power management, material functionalization, sustainable prototyping strategies, new materials, commercialization, and hybridization are discussed. A novel solution is proposed for renewable energy generation and medicinal purposes based on the sustainable utilization of recyclable municipal and medical waste generated during the COVID-19 pandemic. Finally, recommendations for future research are presented concerning the cutting-edge issues hurdling the optimal exploitation of renewable energy resources through NMEHs. China and the USA are the most significant leading forces in enhancing 3DP-NMEH technology, with more than 75% contributions collectively. The reported output energy capacities of additively manufactured nano-MEH systems were 0.5–32 mW, 0.0002–45.6 mW, and 0.3–4.67 mW for electromagnetic, piezoelectric, and triboelectric nanogenerators, respectively. The optimal strategies and techniques to enhance these energy capacities are compiled in this paper. Graphical Abstract
Yanen Wang,Jakiya Sultana,Ammar Ahmed,Ali Azam,Ray Tahir Mushtaq,Mudassar Rehman 한국섬유공학회 2022 Fibers and polymers Vol.23 No.12
The development of bamboo fibre (BF) reinforced poly lactic acid (PLA) BF-PLA composites has been growing fast among the natural fibre reinforced composites (NFRCs) over the past few years. BF-PLA composites have gained significant interest as sustainable alternative materials for the engineering and industrial sectors. BF-PLA composites are getting popular due to their remarkable features such as eco-friendliness, biodegradability, recyclability, low cost, low specific weight, and improved mechanical and thermal properties. In this paper, a schematic review of the BF-PLA composites was conducted in terms of mechanical properties (i.e., tensile properties, flexural properties, and impact strength), thermal characteristics with and without chemical treatment, and creep behaviour. Moreover, the sustainability aspects, including biodegradability and recyclability of BF-PLA composites, have been discussed based on various manufacturing methods. In addition, the utilization of BF-PLA composites in the additive manufacturing industry, sustainable packaging, structural, dielectric, and automotive applications are also described to make elevations toward future research and industrial implementations or commercialization. Furthermore, the effects of 3D printing parameters on the mechanical and physical properties of printed BF-PLA objects have been summarized. Significantly, this paper highlights the limitations and future perspectives of the BF-PLA composites.
Rafique, Rehan,Asi, Muhammad Nadeem,Saqib, Muhammad,Hussain, Muhammad Hammad,Sial, Awais-ur-Rehman,Mushtaq, Aqsa The Korean Society of Veterinary Science 2014 大韓獸醫學會誌 Vol.54 No.1
The jejunum is the longest part of the small intestine and its lumen is mainly involved in the absorption of the nutrients. The present study was conducted to evaluate the effects of metronidazole, ceftriaxoine sodium and their combination on the stenotic index of the end to end jujunal anastomotic site. To accomplish this, 20 healthy stray dogs were subjected to end to end jejunal ansastmosis. Dogs in Group A (control) underwent jejunal anstomosis with no antibiotic prophylaxis, while those in Group B received surgery and metronidazole alone at 50 mg/kg, those in Group C received ceftriaxone sodium intravenously at 30 mg/kg body weight prior to surgery and dogs in Group D were given metronidazole in combination with ceftriaxone sodium at 50 mg/kg and 30 mg/kg, respectively, 2 h before surgical intervention. No significant difference (p > 0.05) in the stenotic index was observed at 14 days after jejunal anastomosis. These findings indicate that prophylactic administration of metronidazole and ceftriaxone sodium alone or in combination had no significant effect on the stenotic index of the jejunum.