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Pervez, Syed Atif,Kim, Doohun,Farooq, Umer,Yaqub, Adnan,Choi, Jung-Hee,Lee, You-Jin,Doh, Chil-Hoon American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.14
<P>This work is a comparative study of the electrochemical performance of crystalline and amorphous anodic iron oxide nanotube layers. These nanotube layers were grown directly on top of an iron current collector with a vertical orientation via a simple one-step synthesis. The crystalline structures were obtained by heat treating the as-prepared (amorphous) iron oxide nanotube layers in ambient air environment. A detailed morphological and compositional characterization of the resultant materials was performed via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Raman spectroscopy. The XRD patterns were further analyzed using Rietveld refinements to gain in-depth information on their quantitative phase and crystal structures after heat treatment. The results demonstrated that the crystalline iron oxide nanotube layers exhibit better electrochemical properties than the amorphous iron oxide nanotube layers when evaluated in terms of the areal capacity, rate capability, and cycling performance. Such an improved electrochemical response was attributed to the morphology and three-dimensional framework of the crystalline nanotube layers offering short, multidirectional transport lengths, which favor rapid Li<SUP>+</SUP> ions diffusivity and electron transport.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2014/aamick.2014.6.issue-14/am501370f/production/images/medium/am-2014-01370f_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am501370f'>ACS Electronic Supporting Info</A></P>
Pervez, Aslam,Ryu, Jeha Cambridge University Press 2011 Robotica Vol.29 No.5
<B>SUMMARY</B><P><I>Independent mobility</I> is one of the major challenges for elderly. Assistive robots must guarantee user's safety. Existing methods to quantitatively express user's safety are not applicable to mobility assistance robots due to <I>physical attachment</I>. This paper proposes a danger index to estimate user's safety during mobility assistance. The formulation and validation of the index is achieved through extensive subjective and objective experimentation. A motion control method is also introduced that uses the proposed danger index for monitoring user's safety and initiating proper safety actions in case of danger. As an example, experimental results with SpiderBot-II are reported in this paper.</P>
Pervez, Syed Atif,Kim, Doohun,Doh, Chil-Hoon,Farooq, Umer,Choi, Hae-Young,Choi, Jung-Hee American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.14
<P>A novel design for an anodic WO<SUB>3</SUB> mesosponge @ carbon has been introduced as a highly stable and long cyclic life Li-ion battery electrode. The nanocomposite was successfully synthesized via single-step electrochemical anodization and subsequent heat treatment in an acetylene and argon gas environment. Morphological and compositional characterization of the resultant materials revealed that the composite consisted of a three-dimensional interconnected network of WO<SUB>3</SUB> mesosponge layers conformally coated with a 5 nm thick carbon layer and grown directly on top of tungsten metal. The results demonstrated that the carbon-coated mesosponge WO<SUB>3</SUB> layers exhibit a capacity retention of 87% after completion of 100 charge/discharge cycles, which is significantly higher than the values of 25% for the crystalline (without carbon coating) or 40% for the as-prepared mesosponge WO<SUB>3</SUB> layers. The improved electrochemical response was attributed to the higher stability and enhanced electrical conductivity offered by the carbon coating layer.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-14/acsami.5b00341/production/images/medium/am-2015-00341b_0008.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b00341'>ACS Electronic Supporting Info</A></P>
Pervez, S.,Kim, D.,Doh, C.H.,Farooq, U.,Yaqub, A.,Choi, J.H.,Lee, Y.J.,Saleem, M. North-Holland 2014 Materials letters Vol.137 No.-
Highly scalable and fast grown TiO<SUB>2</SUB> nanotube layers (TNTs) were utilized as a binder and conductive agent free anode for Li-ion battery (LIB) to obtain high areal capacity. To synthesize the TNTs, a simple electrochemical anodization was carried out in an electrolyte containing lactic acid as an additive. Lactic acid assisted in obtaining nanotube layers of greater length in a very short time with a strong adherence to the Ti substrate. Results showed that the variation in the aspect ratio of the TNTs has a significant impact on the electrochemical performance of the anode material in terms of areal charge/discharge capacity, i.e., longer the length and wider the diameter of the nanotube, higher the capacity and vice versa. For TNTs with a length of up to 38μm, a high areal capacity of ca. 1000μAhcm<SUP>-2</SUP> was achieved after 100 charge/discharge cycles.
WBAN MAC Protocols― Non-Saturation Modeling and Performance Analysis
( Pervez Khan ),( Niamat Ullah ),( Hoon Kim ) 한국인터넷정보학회 2017 KSII Transactions on Internet and Information Syst Vol.11 No.3
The current literature on discrete-time Markov chain (DTMC) based analysis of IEEE 802.15.6 MAC protocols for wireless body area networks (WBANs), do not consider the ACK timeout state, wherein the colliding nodes check the ill fate of their transmissions, while other contending nodes perform backoff check that slot as usual. In this paper, our DTMC model accurately captures the carrier sense multiple access with collision avoidance (CSMA/CA) mechanism of IEEE 802.15.6 medium access control (MAC) and allows the contending nodes performing backoff to utilize the ACK timeout slot during collisions. The compared rigorous results are obtained by considering a non-ideal channel in non-saturation conditions, and CSMA/CA parameters pertaining to UWB PHY of IEEE 802.15.6 MAC protocols.
Pervez, Shahid,Haroon, Saroona,Awan, Dreema Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.15
Background: Mantle-cell lymphoma (MCL) is a unique entity of peripheral B-cell lymphoma that has a discrete morphologic, immunologic, and genetic phenotype, with more common 'classic' and less frequent 'blastoid' and 'pleomorphic' variants, associated with an aggressive clinical course. The aim of this study was to analyze proliferation (Ki-67) indices of 'classic' (c-MCL) and 'blastoid' (b-MCL) variants of a cohort of MCL and to suggest cut off values for the Ki-67 proliferation index in these two subsets. Materials and Methods: MCL cases diagnosed over $4{\frac{1}{2}}$ years at Section of Histopathology, Department of Pathology and Laboratory Medicine, Aga Khan University Hospital, Karachi were retrieved and reviewed. Ki-67 labelling was scored and analysed. Results: A total of 90 of cases of MCL were scrutinized. Mean age ${\pm}SD$ was $60.2{\pm}12.5$ years and the male to female ratio was 4:1, with 67 (75%) cases of c-MCL and 23 (25%) cases of b-MCL. Most samples were lymph node biopsies (n=68), whereas the remainder were from various extranodal sites The mean Ki-67 proliferation index was $29.5%{\pm}14.4%$ in classic variants and $64.4{\pm}15.2%$ for the blastoid variant, the difference being statistically significant (p = 0.029). Conclusions: It was concluded that differential cut-off values of Ki-67 labeling may be used in more objective way to reliably classify MCL into classic or blastoid variants by diagnostic pathologists. We propose a < 40 proliferative index to be suggestive of c-MCL and one of > 50 for the blastoid variant.