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Muhammad Ajaz Hussain,Khawar Abbas,Muhammad Sher,Muhammad Nawaz Tahir,Wolfgang Tremel,Mohammad Saeed Iqbal,Muhammad Amin,Munair Badshah 한국고분자학회 2011 Macromolecular Research Vol.19 No.12
This article presents the synthesis of novel hydroxypropylmethylcellulose (HPMC)-aspirin (ASP) conjugates,i.e. macromolecular prodrugs, through the reaction of HPMC with ASP after its in situ activation by 4-methylbenzenesulfonyl chloride. The highly pure ASP prodrugs obtained by this homogeneous and elegant esterification method were characterized using different spectroscopic and chromatographic techniques. Nanoparticulate drug design was successfully achieved by the conversion of free hydroxyls of the polymer into acetates. Transmission electron microscopy and scanning electron microscopy showed nanoparticle formation with the major population size distribution of around 450 nm. Nevertheless, the pharmacokinetics of the HPMC conjugates were studied using high performance liquid chromatography. The pharmacokinetic data indicated that a single dose of 132.6 mg of HPMC-ASP was well tolerated in animal studies without any adverse effects. The maximum plasma concentration (C_max) of HPMC-ASP was found to be 14.6 μg·L^-1 with a t_max of 1 h. The plasma half-life and clearance and the volume of HPMC-ASP distribution were 4.6 h, 3.23 L·h^-1, and 21.8 L·kg^-1, respectively. The elimination of HPMC-ASP followed first-order kinetics with r^2 of 0.9643. The results presented in this paper show the great potential of HPMCASP as a more effective, safe, and stable prodrug.
An Area-efficient Half-row Pipelined Layered LDPC Decoder Architecture
Sabooh Ajaz,Tram Thi Bao Nguyen,Hanho Lee 대한전자공학회 2017 Journal of semiconductor technology and science Vol.17 No.6
This paper presents an area-efficient half-row pipelined layered low-density parity check (LDPC) decoder architecture for IEEE 802.11ad applications. The proposed decoder achieves a good tradeoff between throughput and area because of its ability to overcome the low-throughput bottleneck in conventional half-row decoders and the high-complexity bottleneck in fully parallel decoders. Synthesis results using TSMC 40 nm CMOS technology shows much better throughput at 10.84 Gbps and superior area efficiency, compared to previously reported LDPC decoders.
( Muhammad Ajaz Ahmed ),( Sadaf Mearaj ),( Joon Weon Choi ) 한국목재공학회 2021 한국목재공학회 학술발표논문집 Vol.2021 No.1
In this study the thermal stability of lignin-PVA composites incorporating epichlorohydrin as well as mxene has been investigated. Initially, a set of experiments was designed to screen out the most feasible soda lignin amount to be incorporated into PVA composites. Interestingly, under ambient convective cooling conditions, 10 wt.% soda lignin exhibited quite brittle and transparent characteristic features but without the addition of either any Epichlorohydrin or Mxene. However, upon the addition of Epichlorohydrin a gradual improvement in the physical features such as ductility as well as shape of the lignin-PVA composites was clearly observed. Additionally, a small amount of Mxene, etched from MAX powder, was added and there was a clear elongation and stretchable trend in the lignin-PVA-Mxene composite as compared with only lignin-PVA only composite. Finally, all the fabricated composites were subjected to thermal stability analysis. It was observed clearly that the addition of both the Epichlorohydrin and Mxene improved the thermal stability of the fabricated composites.
Mild Acidolysis Fractionation of Pinewood Biomass for Lignin Extraction
이자스 ( Muhammad Ajaz Ahmed ),최준원 ( Joon Weon Choi ) 한국목재공학회 2020 한국목재공학회 학술발표논문집 Vol.2020 No.1
Lignocelluloses are the most abundent and readily collectable biomass feedstcoks on this earth and even more with an enough theoratical potential to replace existing fossilfuels based economy. In their typical nature configuration, they are composed of polysaccharides as well as lignin. This lignin is the second most abundant component in their structure and is often a biorefinery waste in a typical 2G bioethanol production schemes. This lignin, actually, is a rich diverse feedstock for the production of various composites, sustainable materials, epoxies and even can be used in medicine and for drug delivery. For this lignin to be isolated with as much little modification as possible is still a challenge for the establishment of lignin-first 2G biorefineries. Therefore, we are trying to adapt and develop such processes that are able to extract/ isolate lignin from the native structure with least and/or no modification. We are applying several organsolv fractionation processes like a green solvent gamma valerolactone (GVL), ethanol, acetone, dioxane and combinations of ethanol, GVL, dioxane and acetone and the synergetic effects of GVL, ethanol under mild acidic and thermal conditions. We have used mild temperature conditions ranging from 50 °C to 90 °C and time ranges from 3 hrs to 6 hrs. In order to induce mild acidic conditions Hcl was employed as a catalyst with few drops only. The lignin fractions separated via this method are subjected to their qualitative analyses such as (Defunctionalization Followed by Random Carbonization) DFRC and Gel permeation chromatography (GPC) to further sort out any clue with their effect on lignin purity and yield.
Optimization of twin gear-based pretreatment of rice straw for bioethanol production
Ahmed, Muhammad Ajaz,Rehman, Muhammd Saif Ur,Terá,n-Hilares, Ruly,Khalid, Saira,Han, Jong-In Elsevier 2017 Energy conversion and management Vol.141 No.-
<P><B>Abstract</B></P> <P>A laboratory twin-gear reactor (TGR) was investigated as a new means for the pretreatment of high solid lignocelluloses. Response surface methodology based on Box Behnken Design was used to optimize the enzymatic digestibility with respect to the pretreatment process variables: temperature of 50–90°C, NaOH concentration of 2–6% and no. of cycles of 30–60. The results revealed that the TGR-based pretreatment led to the significant structural alterations through increases in pore size, pore volume, cellulose crystallinity and surface area. SEM images also confirmed the surface modifications in the pretreated rice straw. A response surface quadratic model predicted 90% of the enzymatic digestibility, and it was confirmed experimentally and through the analysis of variance (ANOVA) as well. The TGR extrusion proved to be an effective means for exceedingly high solids lignocellulose.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Twin gear reactor is a continuous high solids pretreatment reactor. </LI> <LI> RSM was applied to optimize twin gear pretreatment for enzymatic digestibility. </LI> <LI> 89% enzymatic digestibility was achieved under optimum conditions. </LI> <LI> Thermomechanical pretreatment altered the structural features of rice straw. </LI> </UL> </P>
MXene-Lignin Composites for Energy Harvesting Applications from the Ambient Water
( Ahmed Muhammad Ajaz ),( Joon Weon Choi ) 한국목재공학회 2022 한국목재공학회 학술발표논문집 Vol.2022 No.1
Lignin is the second most abundant biorenewable feedstock available on the earth. This lignin, upon carbonisation, exhibits poor graphene like structure. This structure can be employed for energy harvesting applications. On the other hand, MXene is a new 2D materials that have quite good features in terms of their conductivity within the small pores. A combination under the synergism of MXene and lignin derived activated carbon can be a good possibility to harness energy from ambient environment. Therefore, in this study, lignin derived activated carbon was employed along with Mxene-carbon black composite to study their possibility for harnessing energy from ambient water. First, Mxene was etched via HF method from their MAX phase and its analyses such as FTIR, XRD and SEM images were performed to confirmed its successful formation. Lignin derived activated carbon was subjected to make a composite with Mxene & carbon black to finally fabricate a moisture driven power generator (MDPG) by coating the composite onto cellulosic sheets. Finally, the performance of the as prepared MDPG was measured by determining their open circuit voltage (Voc) and short circuit current (Isc). The highest voltage generation was measured as 750 mV and current as 12 μA employing lignin derived activated carbon & Mxene composite. It was also observed that the application of small amount of water 1 ml successfully initiated the moisture assisted power generation for almost 60 minutes in a one go. From here it can be suggested that the lignin derived activated carbon along with Mxene can be used for energy harvesting applications.