Zakir Khan - Academia.edu (original) (raw)

Papers by Zakir Khan

Sensors, 2020

In this paper, a slotted conical patch connected to a small triangular patch multiband antenna fo... more In this paper, a slotted conical patch connected to a small triangular patch multiband antenna for both microwave and millimeter-wave applications is presented. The designed antenna has three characteristics. The proposed antenna is a multiband, having a compact size of 0.35λ0 × 0.35λ0 × 0.004λ0 at its lowest operational frequency, i.e., 2.4 GHz, and more importantly, it can cover both the microwave and millimeter-wave bands with a single feeding. According to the −10 dB matching bandwidth, experimental results show that the antenna operates at (2.450–2.495) GHz, (5.0–6.3) GHz, and (23–28) GHz. The reduced size, simple design, and multiband large bandwidth are some of the advantages over the reported designs in the latest literature. Both simulated and experimental results show a good agreement, and the proposed antenna can be used for wireless local area network (WLAN) applications and fifth-generation (5G) wireless communication devices.

Journal of Biological Chemistry, 2019

Angiotensin-converting enzyme (ACE) affects blood pressure. In addition, ACE overexpression in my... more Angiotensin-converting enzyme (ACE) affects blood pressure. In addition, ACE overexpression in myeloid cells increases their immune function. Using MS and chemical analysis, we identified marked changes of intermediate metabolites in ACE-overexpressing macrophages and neutrophils, with increased cellular ATP (1.7–3.0-fold) and Krebs cycle intermediates, including citrate, isocitrate, succinate, and malate (1.4–3.9-fold). Increased ATP is due to ACE C-domain catalytic activity; it is reversed by an ACE inhibitor but not by an angiotensin II AT1 receptor antagonist. In contrast, macrophages from ACE knockout (null) mice averaged only 28% of the ATP levels found in WT mice. ACE overexpression does not change cell or mitochondrial size or number. However, expression levels of the electron transport chain proteins NDUFB8 (complex I), ATP5A, and ATP5β (complex V) are significantly increased in macrophages and neutrophils, and COX1 and COX2 (complex IV) are increased in macrophages overexp...

2016 Sixth International Conference on Innovative Computing Technology (INTECH), 2016

In this modern life, the digital images are being considered the main source of information shari... more In this modern life, the digital images are being considered the main source of information sharing. The digital images are being used in various fields such as medical imaging, news reporting, crime investigation, insurance claims etc. However, in the presence of sophisticated image editing tools, the credibility of digital images is the main concern. The copy-move forgery (CMF) is a most popular forgery attack. In CMF, a region is duplicated elsewhere in the same image for producing a forged image. Thus, for detecting this particular artifact an algorithm is presented that utilizes Stationary Wavelet Transform (SWT). The experimental results demonstrate that the algorithm is capable of detecting duplicated blocks precisely and identify multiple CMF effectively, even when the images are contaminated by blurring and noise. The performance of our algorithm in comparison with other systems proves the efficacy of the system with a noticeable increase in detection ratios.

International Journal of Advanced Computer Science and Applications, 2016

Audio steganography is used to hide secret information inside audio signal for the secure and rel... more Audio steganography is used to hide secret information inside audio signal for the secure and reliable transfer of information. Various steganography techniques have been proposed and implemented to ensure adequate security level. The existing techniques either focus on the payload or security, but none of them has ensured both security and payload at same time. Data Dependency in existing solution was reluctant for the execution of steganography mechanism serially. The audio data and secret data pre-processing were done and existing techniques were experimentally tested in Matlab that ensured the existence of problem in efficient execution. The efficient least significant bit steganography scheme removed the pipelining hazard and calculated Steganography parallel on distributed memory systems. This scheme ensures security, focuses on payload along with provisioning of efficient solution. The result depicts that it not only ensures adequate security level but also provides better and efficient solution.

2015 13th International Conference on Frontiers of Information Technology (FIT), 2015

Symmetric key cryptography is a common cryptographic technique using the same key at both the tra... more Symmetric key cryptography is a common cryptographic technique using the same key at both the transmitter and receiver side. The main advantage of symmetric key encryption is its less computational cost compared to its counterpart-public key encryption. In this work a new symmetric key encryption scheme is proposed. Rather than using normal binary secret keys, our technique uses images as secret keys. Message letters are converted into their corresponding 8-bit binary codes. These 8-bit codes are scanned for image pixel values which are represented by the same 8-bit codes. When a match is found between the message 8-bit code and pixel values codes that location of the pixel is saved in a separate file. Instead of saving pixel locations as (x, y) coordinates, their locations are saved as one value column wise. After having all matches, pixels locations are transmitted as cipher text. The receiver side will scan the same image for those locations and will pick values at those locations which represent message codes. The main advantage of this scheme is its high security as its key size is very large.

European Scientific Journal, Jul 30, 2013

Background: One third of foreign bodies retained in the gastrointestinal tract are present in the... more Background: One third of foreign bodies retained in the gastrointestinal tract are present in the esophagus. Their management depends on the anatomic location, shape and size of the foreign body and duration of impaction Objective: To determine the frequency, their site of impaction and method of removal of esophageal foreign bodies among patients reporting with aero digestive tract foreign body. Material and Methods This was a Descriptive study conducted at the ENT Department, Ayub Medical Institute (AMI) Abbottabad from June 2011 to June 2012. A total of 100 patients were included in the study presenting with foreign body ingestion that underwent esophagoscopy under general anesthesia. The type and site of impaction of foreign body and method of removal was noted. Results: A total of 100 patients were included with age ranging from 1 to 90 years and the mean age was 14.60 ± 21.13 years. Among the patients with foreign body in aero digestive tract, the foreign body in esophagus was noted in 57% patients. The most common foreign body was coin (56%). The foreign bodies were seen most commonly among children of age 1-5 years (55%). Rigid endoscopy was most common procedure performed to remove the foreign body (84%). Conclusion: Esophageal foreign bodies are most commonly seen among patients with foreign body in aero digestive tract. Coins are the most common type. Rigid endoscopy is most commonly performed procedure to remove them.

Audio steganography is the technique of hiding secret information into the samples of an audio si... more Audio steganography is the technique of hiding secret information into the samples of an audio signal. A number of audio steganographic techniques are available in literature. All the available techniques emphasis on the security of the technique and the payload. Not a single technique promises good security and high payload at the same time. In this work a new least significant bit (LSB) audio steganographic technique is introduced. In this technique secret information is embedded in audio samples based on the amplitude of the sample. The idea is taken from the fact that high amplitude audio samples over run low amplitude samples which means that more information bits can be embedded in low amplitude samples and vice versa. A threshold is set to decide what number of bits to be embeddedin which amplitude sample. This threshold works as a secret key for the information hidden in the audio samples.The proposed technique does not affect the quality of the resultant audio signal and is more secure than the conventional LSB technique.

As a trojan horse mechanism likely supports neurodelivery of infectious particles within monocyte... more As a trojan horse mechanism likely supports neurodelivery of infectious particles within monocytes/macrophages, we currently investigate the biodistribution and brain translocation of inert nanosized particles after i.m. injection. Brain is considered as efficiently protected from circulating elements by blood brain barrier (BBB). The present study aimed at evaluating the influence of BBB integrity in nanoparticle neurodelivery by comparing mice with chronically altered BBB (mdx) and normal controls (C57Bl6). Fluorescent 500nm sized fluorescent particles (20μL) were injected in both tibialis anterior muscles of mdx and C57 mice. At D21 and D90 post-injection, brains were removed, hemispheres separated and treated either for macrophage/microglia (MM) extraction or histology. MM were extracted using CD45-coupled magnetic beads (Miltenyi) and sorted according to their CD11b expression. Sorted cells were thereafter microscopically analyzed on cytospins for their fluorescent bead (fb) co...

The thermal decomposition of palm oil wastes in the form of palm shell and palm oil fronds in the... more The thermal decomposition of palm oil wastes in the form of palm shell and palm oil fronds in the presence of steam and catalyst was experimentally investigated using thermogravimetric analyzer-gas chromatography (TGA-GC). The hydrogen gas composition was observed for palm oil wastes thermal decomposition i) under inert atmosphere (no steam), ii) in steam gasification and iii) in catalytic steam gasification using a newly developed bi metallic catalyst. Detailed discussion has been made for product gas composition profiles at steam-to-biomass ratio of 1 and biomass-to-catalyst ratio of 3. Maximum H2 content up to 64 mol% and 50 mol% in product gas was observed for palm shell and palm oil fronds, respectively, in the catalytic steam gasification. The usage of steam has almost increased H2 content by 28% for both palm oil wastes. The catalyst usage in the steam gasification increased H2 content by 12.5% and 6% for palm shell and palm oil fronds, respectively. Moreover, CO2 concentrati...

Cancer Letters, 2015

The dynamical core of a new sea ice model is presented. It is based on the Elasto-Brittle rheolog... more The dynamical core of a new sea ice model is presented. It is based on the Elasto-Brittle rheology, which is inspired by progressive damage models used for example in rock mechanics. The main idea is that each element can be damaged when the local internal stress exceeds a Mohr-Coulomb failure criterion. The model is implemented with a finite element method and a Lagrangian advection scheme. Simulations of 10 days are performed over the Arctic at a resolution of 7 km. The model, which has only a few parameters, generates discontinuous sea ice velocity fields and strongly localized deformation features that occupy a few percent of the total sea ice cover area but accommodate most of the deformation. For the first time, a sea ice model is shown to reproduce the multifractal scaling properties of sea ice deformation. The sensitivity to model parameters and initial conditions is presented, as well as the ability of the Lagrangian advection scheme at preserving discontinuous fields.

ABSTRACT Steganography is the art of hiding user information in various file types including imag... more ABSTRACT Steganography is the art of hiding user information in various file types including image, audio and video. Security of steganography lies in imperceptibility of secret information in the cover image. Human visual system (HVS) is not able to detect the changes in low color values of an image. To the best of our knowledge, none of the available steganographic techniques have exploited this weakness of HVS. In this paper, a new LSB technique is presented which hides information in the cover image taking into account the pixel value of color or grey level of every pixel. Our experiments show that the proposed technique has a high payload and low perceptibility of secret information hidden in the cover image as compared to the existing LSB based algorithms. We have used MATLAB for the implementation of our algorithm.

Romanian Review of Laboratory Medicine, 2013

Introduction: Multidrug-resistant tuberculosis (MDR-TB) represents an important public health pro... more Introduction: Multidrug-resistant tuberculosis (MDR-TB) represents an important public health problem. Rapid molecular methods detect the mutations responsible for drug-resistance and can shorten the time required for diagnosis and initiation of appropriate therapy. The objectives of our study were to optimize a multiplex allele-specific PCR technique (MAS-PCR) to detect rpoB mutations and to specify the type and frequency of these mutations. Material and methods: We have tested 47 non-duplicate MDR-TB, including extensively drugresistant tuberculosis (XDR-TB) strains, identified during 2007-2012, using MAS-PCR for detection of mutations in rpoB codons 531, 526 and 516. Results: The most common mutation was located in codon 531 (63.82%), while only 12.76% and 10.63% of the strains showed mutations in codon 516 and 526, respectively; for six strains we have not identified mutation in the targeted codons. Conclusion: MAS-PCR revealed the mutations prevalent in our region, with good sensitivity (87.2%), suggesting the usefulness of this test in the rapid diagnosis of MDR-TB.

Current Medicinal Chemistry, 2014

Peptides and proteins are the natural means of activating and inhibiting cellular mechanisms. Nor... more Peptides and proteins are the natural means of activating and inhibiting cellular mechanisms. Normal functions of the central nervous system (CNS) largely dependent on protein-protein interactions (PPIs) signaling pathways. Affecting receptors and targets of naturally occurring peptides and proteins is a very promising therapeutic strategy for the treatment of neurodegenerative diseases. PPIs can be readily addressed with small molecule drugs. Several small-molecule drugs that do address PPIs are natural products. Since last two decades extensive research is going on to explore other approaches for targeting specific intracellular PPIs. After many years of stagnation, peptide therapeutics once again became the focus of innovative drug development efforts backed up by venture funds and biotechnology companies.

Current Opinion in Pharmacology, 2015

Hypertension is a major risk factor for cardiovascular disease. While the cause of hypertension i... more Hypertension is a major risk factor for cardiovascular disease. While the cause of hypertension is multifactorial, renal dysregulation of salt and water excretion is a major factor. All components of the renin angiotensin system are produced locally in the kidney, suggesting that intrarenal generation of angiotensin II plays a key role in blood pressure regulation. Here, we show that two mouse models lacking renal angiotensin converting enzyme (ACE) are protected against angiotensin II and L-NAME induced hypertension. In response to hypertensive stimuli, mice lacking renal ACE do not produce renal angiotensin II. These studies indicate that the intrarenal renin angiotensin system works as an entity separate from systemic angiotensin II generation. Renal ACE appears necessary for experimental hypertension.

Applied Mechanics and Materials, 2014

In Malaysia, due to its abundance, oil palm is a good candidate to be used as a feedstock for hyd... more In Malaysia, due to its abundance, oil palm is a good candidate to be used as a feedstock for hydrogen production. Oil palm biomass generally consists of cellulose, hemicellulose and lignin. Steam gasification, coupled with CO2 removal has been shown to be one of the promising methods for hydrogen production. This work focuses on the mathematical modeling of hydrogen production from cellulose via steam gasification and steam gasification with in-situ CO2 capture using CaO. The results are compared and rationalized against published data on steam gasification of pure cellulose and good agreement is observed. The model predicts an increase in hydrogen output from 48 to 56 mol% with the addition of CaO into the system. By increasing temperature and steam/biomass ratio the cold gas efficiency decreases, however, temperature have higher impact compared to steam/biomass ratio.

Advanced Materials Research, 2014

There is a need to search for efficient material that reduce CO2 content and enhance the hydrogen... more There is a need to search for efficient material that reduce CO2 content and enhance the hydrogen composition in the product gas from biomass steam gasification particularly for large scale production. The present study was carried out to perform the characterization of commercial quicklime as CO2 absorbent and Ni powder as catalyst. The chemical composition of the materials perform using x-ray fluorescence (XRF) indicated high amount of CaO and Ni in the bulk samples. Using XRF and SEM analyses, it was found that both materials showed high crystalinity. The adsorption isotherm from physisorption analysis suggested that the materials exhibits Type II category according to the IUPAC classification scheme. These types of material exhibit mesoporous structure which was also verified by the pore size of the samples found via BET analysis. The BET surface area reported was 4.16 m2/g and 0.78 m2/g for quicklime and Ni powder, respectively. In conclusion, commercial quicklime has the poten...

Science Signaling, 2012

The G protein of rabies virus manipulates the cellular localization of PTEN, which may promote ce... more The G protein of rabies virus manipulates the cellular localization of PTEN, which may promote cell survival.