| 1. |
- Bhatti, Adeel Liaquat, et al.
(författare)
-
An Efficient and Functional Fe3O4/Co3O4 Composite for Oxygen Evolution Reaction
- 2021
-
Ingår i: Journal of Nanoscience and Nanotechnology. - : AMER SCIENTIFIC PUBLISHERS. - 1533-4880 .- 1533-4899. ; 21:4, s. 2675-2680
-
Tidskriftsartikel (refereegranskat)abstract
- The design of efficient, stable, durable and noble metal free electro catalysts for oxygen evolution reaction (OER) are of immediate need, but very challenging task. In this study, iron induction into cobalt oxide (Co3O4) has resulted composite structure by wet chemical method. The iron impurity has brought an electronic disorder into Fe3O4/cobalt oxide composite thereby efficient oxygen evolution reaction is demonstrated. An addition of iron content into composite resulted the alternation of morphology from Nano rods to clusters of nanoparticles. The successive addition of iron into composite system reduced the onset potential of OER as compared to the pristine cobalt oxide. A Tafel slope of 80 mVdec(-1) indicates the favorable oxygen evolution reaction kinetics on the sample 4. An over-potential of 370 mV is required to reach a 10 mAcm(-2) current density which is acceptable for a nonprecious catalyst. The catalyst is highly durable and stable for 30 hours. Electrochemical impedance spectroscopy further provided a deeper insight on charge transfer resistance and sample 4 has low charge transfer resistance that supported the OER polarization curves. The sample 4 has more electrochemical active surface area of 393.5 cm(2). These obtained results are exciting and highlighting the importance of composite structure and leave a huge space for the future investigations on composite materials for energy related applications.
|
|
| 2. |
- Asif, Muhammad, et al.
(författare)
-
The Effect of Infrared Laser Irradiation on the Surface Morphology and Electrical Properties of Zinc Metal
- 2023
-
Ingår i: Physchem. - : MDPI AG. - 2673-7167. ; 3:1, s. 22-33
-
Tidskriftsartikel (refereegranskat)abstract
- This study details the irradiation of pure (99.995%) and immaculate metallic Zinc using Nd: YAG laser (1064 nm, 10 mJ, 9–14 ns). The influence and impact of multiple laser shots on the formation of microstructures and crystal structure orientations is assessed. Arrays of ablated craters are machined on the whole surface of the target to probe the electrical and topographical characteristics of laser-treated surfaces. Irradiated samples are examined by multiple characterizing techniques such as scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffraction (XRD), and a four-point probe for electrical conductivity measurements. SEM and AFM analysis exhibited the formation of laser-induced ripple structures with periodicity sheerly dependent on laser shots. A comparison of surface topography of the virgin and treated samples disclosed a pronounced modification in surface texture. The XRD patterns of laser shined targets indicate no momentous structural change in the crystal structure, whereas the measurements on the electrical conductivity of the irradiated surfaces exhibit an exponential descending trend with an augmentation in laser shots.
|
|
| 3. |
- Bhatti, Adeel Liaquat, et al.
(författare)
-
Facile doping of nickel into Co3O4 nanostructures to make them efficient for catalyzing the oxygen evolution reaction
- 2020
-
Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:22, s. 12962-12969
-
Tidskriftsartikel (refereegranskat)abstract
- Designing a facile and low-cost methodology to fabricate earth-abundant catalysts is very much needed for a wide range of applications. Herein, a simple and straightforward approach was developed to tune the electronic properties of cobalt oxide nanostructures by doping them with nickel and then using them to catalyze the oxygen evolution reaction (OER) in an aqueous solution of 1.0 M KOH. The addition of a nickel impurity improved the conductivity of the cobalt oxide, and further increased its activity towards the OER. Analytical techniques such as scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and powder X-ray diffraction (XRD) were used to investigate, respectively, the morphology, composition and crystalline structure of the materials used. The nickel-doped cobalt oxide material showed randomly oriented nanowires and a high density of nanoparticles, exhibited the cubic phase, and contained cobalt, nickel and oxygen as its main elements. The nickel-doped cobalt oxide also yielded a Tafel slope of 82 mV dec(-1) and required an overpotential of 300 mV to reach a current density of 10 mA cm(-2). As an OER catalyst, it was shown to be durable for 40 h. Electrochemical impedance spectroscopy (EIS) analysis showed a low charge-transfer resistance of 177.5 ohms for the nickel-doped cobalt oxide, which provided a further example of its excellent OER performance. These results taken together indicated that nickel doping of cobalt oxide can be accomplished via a facile approach and that the product of this doping can be used for energy and environmental applications.
|
|
| 4. |
- Asim, Muhammad, et al.
(författare)
-
Experimental analysis of solar thermal integrated MD system for cogeneration of drinking water and hot water for single family villa in Dubai using flat plate and evacuated tube solar collectors
- 2017
-
Ingår i: Desalination and Water Treatment. - : DESALINATION PUBL. - 1944-3994 .- 1944-3986. ; 92, s. 46-59
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the experimental analysis performed on solar thermal integrated membrane distillation (MD) system using flat plate and evacuated tube collectors. The system will be utilized for cogeneration of drinking water and domestic hot water for single family in Dubai comprising of four to five members. Experiments have been performed in Ras Al Khaimah Research and Innovation Centre (RAKRIC) facility. The experimental setup has been installed to achieve the required production of 15-25 L/d of drinking water and 250 L/d of hot water for domestic purposes. Experiments have been performed on MD setup at optimized flow rates of 6 L/min on hot side and 3 L/min on cold side for producing the desired distillate. The hot side and cold side MD temperature has been maintained between 60 degrees C and 70 degrees C, and 20 degrees C and 30 degrees C. The total annual energy demand comes out to be 8,223 kWh (6,000 kWh is for pure water and 2,223 kWh for hot water). The optimum aperture areas for flat plate and evacuated tube collector field have been identified as 8.5 and 7.5 m(2), respectively. Annual energy consumption per liter for pure water production is 1, 0.85 and 0.7 kWh/L for different MD hot and cold inlet temperatures.
|
|
| 5. |
- Aslam, Bilal, et al.
(författare)
-
A low profile miniature RFID tag antenna dedicated to IoT applications
- 2019
-
Ingår i: Electromagnetics. - : Taylor & Francis. - 0272-6343 .- 1532-527X. ; 39:6, s. 393-406
-
Tidskriftsartikel (refereegranskat)abstract
- RFID tag antennas with stable performance on the diverse electromagnetic mounting platforms are an integral part of the ubiquitous RFID systems. This research article presents a novel tag antenna design that facilitates the said objective. The proposed antenna consists of a modified H-shaped slot structure that ensures considerable robustness from the application environment through confining the surface current density within the antenna structure. The antenna offers a tunable bandwidth of 40 MHz within the microwave band of (2.4-2.5) GHz. The proposed tag antenna exhibits excellent response on metallic platforms of different sizes and thicknesses with an effective gain of almost four times of that in free space. Furthermore, the designed tag antenna performs adequately well on low-medium permittivity dielectrics (glass, paper, and plastic) and RF absorbers (water). The free space and on-metal performance of the proposed tag antenna are verified by testing a prototype realized on the FR4 substrate.
|
|
| 6. |
- Fakhar-e-Alam, Muhammad, et al.
(författare)
-
Sensitivity of A-549 human lung cancer cells to nanoporous zinc oxide conjugated with Photofrin
- 2012
-
Ingår i: Lasers in Medical Science. - : Springer Verlag (Germany). - 0268-8921 .- 1435-604X. ; 27:3, s. 607-614
-
Tidskriftsartikel (refereegranskat)abstract
- In the present study, we demonstrated the use of nanoporous zinc oxide (ZnO NPs) in photodynamic therapy. The ZnO NPs structure possesses a high surface to volume ratio due to its porosity and ZnO NPs can be used as an efficient photosensitizer carrier system. We were able to grow ZnO NPs on the tip of borosilicate glass capillaries (0.5 mu m diameter) and conjugated this with Photofrin for efficient intracellular drug delivery. The ZnO NPs on the capillary tip could be excited intracellularly with 240 nm UV light, and the resultant 625 nm red light emitted in the presence of Photofrin activated a chemical reaction that produced reactive oxygen species (ROS). The procedure was tested in A-549 cells and led to cell death within a few minutes. The morphological changes in necrosed cells were examined by microscopy. The viability of control and treated A-549 cells with the optimum dose of UV/visible light was assessed using the MTT assay, and ROS were detected using a fluorescence microscopy procedure.
|
|
| 7. |
- Munawar, Saira, et al.
(författare)
-
Future Climate Projections Using SDSM and LARS-WG Downscaling Methods for CMIP5 GCMs over the Transboundary Jhelum River Basin of the Himalayas Region
- 2022
-
Ingår i: Atmosphere. - : MDPI. - 2073-4433. ; 13:6
-
Tidskriftsartikel (refereegranskat)abstract
- Climate change is one of the leading issues affecting river basins due to its direct impacts on the cryosphere and hydrosphere. General circulation models (GCMs) are widely applied tools to assess climate change but the coarse spatial resolution of GCMs limit their direct application for local studies. This study selected five CMIP5 GCMs (CCSM4, HadCM3, GFDL-CM3, MRI-CGCM3 and CanESM2) for performance evaluation ranked by Nash–Sutcliffe coefficient (NSE) and Kling–Gupta Efficiency (KGE). CCSM4 and HadCM3 large-scale predictors were favored based on ranks (0.71 and 0.68, respectively) for statistical downscaling techniques to downscale the climatic indicators Tmax, Tmin and precipitation. The performance of two downscaling techniques, Statistical Downscaling Methods (SDSM) and Long Ashton Research Station Weather Generator (LARS-WG), were examined using the Mean Absolute Error (MAE), Root Mean Square Error (RMSE), bias, NSE and KGE with weights (Wi) for the validation period. The results of statistical measures proved SDSM more efficient (0.67) in comparison to the LARS-WG (0.51) for the validation time for the Jhelum River basin. The findings revealed that the SDSM simulation for Tmax and Tmin are more comparable to the reference data for the validation period except simulation of extreme events by precipitation. The 21st century climatic projections exhibited a significant rise in Tmax (2.37–4.66 °C), Tmin (2.47–4.52 °C) and precipitation (7.4–11.54%) for RCP-4.5 and RCP-8.5, respectively. Overall, the results depicted that winter and pre-monsoon seasons were potentially most affected in terms of warming and precipitation, which has the potential to alter the cryosphere and runoff of the Jhelum River basin.
|
|
| 8. |
- Munsif, Fazal, et al.
(författare)
-
Dual-purpose wheat technology : a tool for ensuring food security and livestock sustainability in cereal-based cropping pattern
- 2021
-
Ingår i: Archives of Agronomy and Soil Science. - : Taylor & Francis Group. - 0365-0340 .- 1476-3567. ; 67:13, s. 1889-1900
-
Tidskriftsartikel (refereegranskat)abstract
- Wheat cultivation under a dual-purpose (DP) system holds great potential to provide additional fodder for livestock with marginal grain reduction. This study explores the potential of wheat as a DP crop for improving both, forage and grain cropping system by finding out optimal sowing dates and cultivars suitable for DP cropping. Field experiments with four cultivars (Saleem-2000, Bathoor-2007, Fakhre Sarhad-99 (FS-99) and Siran-2008), three sowing dates (October 15, October 30 and November 15) and two cutting treatments (cut and no-cut) determines the effects on yield and physiology of wheat. Wheat sown either in mid or end of October resulted in 11 and 8% increase in grain yield while 13 and 9% in biological yield over mid November sowing, respectively. This increase in yield was due to higher grain spike(-1), chlorophyll content, transpiration rate and relative water content. The cultivars Siran-2008 and Saleem-2000 had higher biological and grain yields than other cultivars across cutting and sowing dates treatments. Biological and grain yields were reduced by 4% and 3%, respectively under the DP wheat compared with no-cut treatment, but grains N content was unaffected. Conclusively, DP wheat system (cut treatment) had higher profitability (11.2%) than wheat crop sown only for grain purposes.
|
|
| 9. |
- Shahid, Muhammad Kashif, et al.
(författare)
-
Chapter 10 - Circular bioeconomy perspective of agro-waste-based biochar
- 2022
-
Ingår i: Biomass, Biofuels, Biochemicals. - : Elsevier. - 9780323885119 ; , s. 223-243
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter focuses on the synthesis and application of agro-waste-based biochar with a perspective of circular bioeconomy. Numerous methods are known for the synthesis of biochar; however, pyrolysis of agro-waste is the highly acclaimed method for biochar production from agro-waste. Biochar production is influenced by multiple factors including nature and source of feedstock, pyrolysis conditions, and the system/device used for thermal treatment. The biochar properties enable it to be applied in several fields including wastewater treatment, soil improvement, reduction of greenhouse gas emissions, carbon sequestration, sludge improvement, etc. The commissioning and erection of production facilities nearby agro-waste production sites, can reduce the supply chain and transport, and also improve the sustainability and development of circular bioeconomy. The application of biochar in water treatment can reduce the burden on market for the production and application of expensive adsorbents and hence, the agro-waste-based green adsorbent (biochar) can enhance bio-sustainability and subsequently circular bioeconomy.
|
|
| 10. |
- Aslam, Bilal, et al.
(författare)
-
Low-profile magnetically coupled dual resonance patch antenna for UHF RFID applications
- 2021
-
Ingår i: AEU - International Journal of Electronics and Communications. - : Elsevier BV. - 1434-8411 .- 1618-0399. ; 133
-
Tidskriftsartikel (refereegranskat)abstract
- A novel low-profile metal mountable UHF RFID tag antenna is presented. The tag antenna design consists of two resonating patches with different resonant frequencies fed through a joint inductive loop. This design topology offers benefits such as bandwidth enhancement in the single band and the possibility of attaining a tunable dualband coverage in the UHF RFID band. The proposed antenna structure doesn't require any electrical connection (shorting pins/shorting plates/via holes) and therefore facilitates fabrication through a conventional RFID inlay manufacturing process. Fabrication and testing of a prototype of the proposed antenna design are carried out. The prototype antenna achieves free space and an on-metal reading range of better than 8 m and 11 m respectively in the US RFID band of 902-928 MHz.
|
|
| 11. |
- Aslam, Muhammad Kashif, et al.
(författare)
-
How to avoid dendrite formation in metal batteries : Innovative strategies for dendrite suppression
- 2021
-
Ingår i: Nano Energy. - : Elsevier. - 2211-2855 .- 2211-3282. ; 86
-
Forskningsöversikt (refereegranskat)abstract
- With increasing the diversity of electronic/electric appliances and large-scale energy storage systems, highenergy-density based device technology has been in great demand. Meanwhile, for developing of high-voltage and high-capacity cathode, the use of metals including lithium (Li), sodium (Na), potassium (K), or zinc (Zn) is quite impressive to replace the traditional anodes with low capacity upper limit such as graphite, silicon carbon, and hard carbon which is considered as "holy grail" strategy to explore high-energy density systems. However, these so-called metal batteries (MBs) also face many thorny issues including high anode reactivity, dendritic growth, and high safety risks. Among all these muddle, the dendrite growth is quite sever issue and has attracted much attention of many recognized materials scientist and battery researchers. The formation of dendrite increase the surface area of metal anodes, induce the rupture and reconstruction of solid electrolyte interphase (SEI) film, which is likely to accelerate the excessive consumption of electrolyte and the formation of dead metals. Consequently, battery lose its capability and short circuit produced which causes serious safety issues. Therefore, it is badly needed to inhibit or even eliminate the formation of dendrites during the repeated charge and discharge process to find advanced and fast battery technology. In this review, we summarize the basic mechanistic theoretical models about dendrites formation and their effects on the battery performance. Moreover, we recapitulate the reported literature about dendrites concept and their solution from battery invention to its modernism for smart electric appliances and zero emission electric vehicles. Besides, perspective of interface energy/volume stress, several innovative strategies for restraining, regulating and eliminating dendrites are also part of this review. Finally, perspectives conclusions for the development of MBs about dendrite level are given for the progress of future battery science.
|
|
| 12. |
- Furer, Sebastian O., et al.
(författare)
-
The Performance-Determining Role of Lewis Bases in Dye-Sensitized Solar Cells Employing Copper-Bisphenanthroline Redox Mediators
- 2020
-
Ingår i: Advanced Energy Materials. - : Wiley-VCH Verlagsgesellschaft. - 1614-6832 .- 1614-6840. ; 10:37
-
Tidskriftsartikel (refereegranskat)abstract
- Copper redox mediators have enabled open-circuit voltages (V-OC) of over 1.0 V in dye-sensitized solar cells (DSCs) and have helped to establish DSCs as the most promising solar cell technology in low-light conditions. The addition of additives such as 4-tert-butylpyridine (tBP) to these electrolytes has helped in achieving high solar cell performances. However, emerging evidence suggests that tBP coordinates to the Cu(II) species and limits the performance of these electrolytes. To date, the implications of this coordination are poorly understood. Here, the importance of Lewis base additives for the successful implementation of copper complexes as redox mediators in DSCs is demonstrated. Two redox couples, [Cu(dmp)(2)](+/2+)and [Cu(dpp)(2)](+/2+)(with dmp = 2,9-dimethyl-1,10-phenanthroline and dpp = 2,9-diphenyl-1,10-phenanthroline) in combination with three different Lewis bases, TFMP (4-(trifluoromethyl)pyridine), tBP, and NMBI (1-methyl-benzimidazole), are considered. Through single-crystal X-ray diffraction analysis, absorption, and(1)H-NMR spectroscopies, the coordination of Lewis bases to the Cu(II) centers are studied. This coordination efficiently suppresses recombination losses and is crucial for high performing solar cells. If, however, the coordination involves a ligand exchange, as is the case for [Cu(dpp)(2)](+/2+), the redox mediator regeneration at the counter electrode is significantly retarded and the solar cells show current limitations.
|
|
| 13. |
- Haneef, Tahir, et al.
(författare)
-
Recent progress in two dimensional Mxenes for photocatalysis : a critical review
- 2023
-
Ingår i: 2D Materials. - : Institute of Physics (IOP). - 2053-1583. ; 10:1
-
Forskningsöversikt (refereegranskat)abstract
- Transition metal carbides and nitrides, generally known as MXenes have emerged as an alternative to improve photocatalytic performance in renewable energy and environmental remediation applications because of their high surface area, tunable chemistry, and easily adjustable elemental compositions. MXenes have many interlayer groups, surface group operations, and a flexible layer spacing that makes them ideal catalysts. Over 30 different members of the MXenes family have been explored and successfully utilized as catalysts. Particularly, MXenes have achieved success as a photocatalyst for carbon dioxide reduction, nitrogen fixation, hydrogen evolution, and photochemical degradation. The structure of MXenes and the presence of hydrophilic functional groups on the surface results in excellent photocatalytic hydrogen evolution. In addition, MXenes' surface defects provide abundant CO2 adsorption sites. Moreover, their highly efficient catalytic oxidation activity is a result of their excellent two-dimensional nanomaterial structure and high-speed electron transport channels. This article comprehensively discusses the structure, synthesis techniques, photocatalytic applications (i.e. H-2 evolution, N-2 fixation, CO2 reduction, and degradation of pollutants), and recyclability of MXenes. This review also critically evaluates the MXene-based heterostructure and composites photocatalyst synthesis process and their performance for organic pollutant degradation. Finally, a prospect for further research is presented in environmental and energy sciences.
|
|
| 14. |
- Huang, V., et al.
(författare)
-
Semantic sensor information description and processing
- 2008
-
Ingår i: Proc. - Int. Conf. Sensor Technol. Appl. SENSORCOMM, Incl., MESH: Int. Conf. Adv. Mesh Netw., ENOPT: Int. Workshop Energy Opt. - 9780769533308 ; , s. 456-461
-
Konferensbidrag (refereegranskat)abstract
- Wireless sensor networks (WSN) generate large volumes of raw data which possess natural heterogeneity. WSNs are normally application specific with no sharing or reusability of sensor data among applications. In order for applications and services to be developed independently of particular WSNs, sensor data need to be enriched with semantic information. In this paper, we propose a Semantic Web Architecture for Sensor Networks (SWASN). This information oriented architecture allows the sensor data to be understood and processed in a meaningful way by a variety of applications with different purposes. We develop ontologies for sensor data and use the Jena API for processing which includes querying and inference over sensor data. By studying a building fire emergency scenario, we show that semantic web technologies can provide high level information extraction and inference of sensor data.
|
|
| 15. |
- Kashif, Ahsan-Ullah, et al.
(författare)
-
A TCAD approach for non-linear evaluation of microwave power transistor and its experimental verification by LDMOS
- 2010
-
Ingår i: Journal of Computational Electronics. - : SpringerLink. - 1569-8025 .- 1572-8137. ; 9:2, s. 79-86
-
Tidskriftsartikel (refereegranskat)abstract
- A simulation technique is developed in TCAD to study the non-linear behavior of RF power transistor. The technique is based on semiconductor transport equations to swot up the overall non-linearity’s occurring in RF power transistor. Computational load-pull simulation technique (CLP) developed in our group, is further extended to study the non-linear effects inside the transistor structure by conventional two-tone RF signals, and initial simulations were done in time domain. The technique is helpful to detect, understand the phenomena and its mechanism which can be resolved and improve the transistor performance. By this technique, the third order intermodulation distortion (IMD3) was observed at different power levels. The technique was successfully implemented on a laterally-diffused field effect transistor (LDMOS). The value of IMD3 obtained is −22 dBc at 1-dB compression point (P 1 dB) while at 10 dB back off the value increases to −36 dBc. Simulation results were experimentally verified by fabricating a power amplifier with the similar LDMOS transistor.
|
|
| 16. |
- Kashif, Ahsan-Ullah, et al.
(författare)
-
A TCAD Approach to Design a Broadband Power Amplifier
- 2010
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Technology Computer Aided Design (TCAD) provides an alternate method to study the power amplifier (PA) design prior to fabrication. It is very useful for the extraction of an accurate large signal model. This paper presents a design approach from device to circuit level to study broadband PA performance of RF-LDMOS using computational load-pull (CLP) analysis. To validate the TCAD approach, we have designed a broadband (1.9 - 2.5 GHz) class AB power amplifier. The concept is verified by designing an output broadband matching network at optimum impedance value (Zf) of RF-LDMOS using ADS software. The large signal results verify this concept and RF output power of 30.8 dBm is achieved with comparable gain and efficiency.
|
|
| 17. |
- Kashif, Ahsan-Ullah, et al.
(författare)
-
Switching Behavior of Microwave Power Transistor Studied in TCAD for Switching Class Power Amplifiers and Experimental Verification by LDMOS based Class-F Power Amplifier
- 2010
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- This paper presents a TCAD study of high speed switching behavior of RF power-transistor in class-F Power Amplifier. We utilized finite harmonics loads for achieving maximum efficiency, without external circuitry. The in house developed computational load–pull (CLP) simulation technique is further extended to investigate the odd harmonic effects of RF transistor in class-F operation. An LD-MOSFET is studied which provided 81.2 % power added efficiency (PAE) at 1 GHz. The concept is experimentally verified by fabricating a class-F PA using same transistor. In the measurement, 76 % PAE is achieved, which is close to the TCAD simulated results. TCAD is an excellent tool to study the behavior of active devices. It has an ability to enhance and optimize the performance of transistor according to system specifications before fabrication.
|
|
| 18. |
- Kashif, Muhammad, et al.
(författare)
-
A Pragmatic Definition of Therapeutic Synergy Suitable for Clinically Relevant In Vitro Multicompound Analyses
- 2014
-
Ingår i: Molecular Cancer Therapeutics. - 1535-7163 .- 1538-8514. ; 13:7, s. 1964-1976
-
Tidskriftsartikel (refereegranskat)abstract
- For decades, the standard procedure when screening for candidate anticancer drug combinations has been to search for synergy, defined as any positive deviation from trivial cases like when the drugs are regarded as diluted versions of each other (Loewe additivity), independent actions (Bliss independence), or no interaction terms in a response surface model (no interaction). Here, we show that this kind of conventional synergy analysis may be completely misleading when the goal is to detect if there is a promising in vitro therapeutic window. Motivated by this result, and the fact that a drug combination offering a promising therapeutic window seldom is interesting if one of its constituent drugs can provide the same window alone, the largely overlooked concept of therapeutic synergy (TS) is reintroduced. In vitro TS is said to occur when the largest therapeutic window obtained by the best drug combination cannot be achieved by any single drug within the concentration range studied. Using this definition of TS, we introduce a procedure that enables its use in modern massively parallel experiments supported by a statistical omnibus test for TS designed to avoid the multiple testing problem. Finally, we suggest how one may perform TS analysis, via computational predictions of the reference cell responses, when only the target cell responses are available. In conclusion, the conventional error-prone search for promising drug combinations may be improved by replacing conventional (toxicology-rooted) synergy analysis with an analysis focused on (clinically motivated) TS.
|
|
| 19. |
- Kashif, Muhammad, et al.
(författare)
-
Bliss and Loewe interaction analyses of clinically relevant drug combinations in human colon cancer cell lines reveal complex patterns of synergy and antagonism
- 2017
-
Ingår i: Oncotarget. - : IMPACT JOURNALS LLC. - 1949-2553. ; 8:61, s. 103952-103967
-
Tidskriftsartikel (refereegranskat)abstract
- We analyzed survival effects for 15 different pairs of clinically relevant anticancer drugs in three iso-genic pairs of human colorectal cancer carcinoma cell lines, by applying for the first time our novel software (R package) called COMBIA. In our experiments iso-genic pairs of cell lines were used, differing only with respect to a single clinically important KRAS or BRAF mutation. Frequently, concentration dependent but mutation independent joint Bliss and Loewe synergy/antagonism was found statistically significant. Four combinations were found synergistic/antagonistic specifically to the parental (harboring KRAS or BRAF mutation) cell line of the corresponding iso-genic cell lines pair. COMBIA offers considerable improvements over established software for synergy analysis such as MacSynergy (TM) II as it includes both Bliss (independence) and Loewe (additivity) analyses, together with a tailored non-parametric statistical analysis employing heteroscedasticity, controlled resampling, and global (omnibus) testing. In many cases Loewe analyses found significant synergistic as well as antagonistic effects in a cell line at different concentrations of a tested drug combination. By contrast, Bliss analysis found only one type of significant effect per cell line. In conclusion, the integrated Bliss and Loewe interaction analysis based on non-parametric statistics may provide more robust interaction analyses and reveal complex patterns of synergy and antagonism.
|
|
| 20. |
- Kashif, Muhammad, et al.
(författare)
-
In vitro discovery of promising anti-cancer drug combinations using iterative maximisation of a therapeutic index
- 2015
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- In vitro-based search for promising anti-cancer drug combinations may provide important leads to improved cancer therapies. Currently there are no integrated computational-experimental methods specifically designed to search for combinations, maximizing a predefined therapeutic index (TI) defined in terms of appropriate model systems. Here, such a pipeline is presented allowing the search for optimal combinations among an arbitrary number of drugs while also taking experimental variability into account. The TI optimized is the cytotoxicity difference (in vitro) between a target model and an adverse side effect model. Focusing on colorectal carcinoma (CRC), the pipeline provided several combinations that are effective in six different CRC models with limited cytotoxicity in normal cell models. Herein we describe the identification of the combination (Trichostatin A, Afungin, 17-AAG) and present results from subsequent characterisations, including efficacy in primary cultures of tumour cells from CRC patients. We hypothesize that its effect derives from potentiation of the proteotoxic action of 17-AAG by Trichostatin A and Afungin. The discovered drug combinations against CRC are significant findings themselves and also indicate that the proposed strategy has great potential for suggesting drug combination treatments suitable for other cancer types as well as for other complex diseases.
|
|
| 21. |
|
|
| 22. |
- Kashif, Muhammad
(författare)
-
Integrated Computational and Experimental Approaches for Accelerated Drug Combination Discovery and Development : Applications in Cancer Pharmacology
- 2015
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Today the norm in modern cancer treatment is to use different forms of drug combinations. Recently anti-cancer treatment using drug combinations has gained increased attention due to the outstanding pharmacotherapeutic opportunities provided by combination therapies. However, the potential of this field is largely unexplored, partly due to the complexities associated with the astronomical number of possible combinations and partly due to the lack of means for quantifying clinically relevant adverse side effects in the early stages of the combination discovery and development process. This has resulted in relatively limited progress in this area. Motivated by this unfortunate state-of-affairs, the research reported in this thesis was aimed at developing and implementing computational and experimental methods to facilitate and accelerate the discovery and development of anti-cancer therapies. In paper I, the largely overlooked concept of therapeutic synergy is re-introduced and demonstrated to be useful already at the level of combination discovery by taking both curative and adverse effects into account. In paper II, a semiautomatic combination discovery platform was developed based on a tailored programming of a pipetting robot system and application of a new in-house developed combination search algorithm, the therapeutic algorithmic combinatorial screen (TACS) algorithm. TACS seems to be the first algorithm of its kind that takes experimental variability into account during the iterative search process. The semiautomatic hardware platform along with TACS can perform de novo or knowledge based combination drug discovery and development without brute force comprehensive search efforts. One promising discovery made using this platform is a combination of the drugs 17-AAG, afungin and trichostatin a for treatment of colorectal cancer carcinoma (CRC). In paper III, an algorithm is developed and applied in order to use single drug induced systemic gene expression profiles for rational drug combination design by assuming additive combination effects. The resulting algorithm, combo-CMap, is applied and validated using a slightly extended version of the freely available Connectivity Map (CMap) database which is currently containing 6190 chemically induced mRNA gene expression signatures. In paper IV, a software (R package) was developed and applied to perform improved synergy/antagonism analysis, in particular joint Loewe and Bliss analyses while taking associated experimental variability into account using non-parametric statistics including bootstrap intervals. Applying this software to the synergy analysis of interaction effects among clinically used and/or relevant drugs in CRC cell lines revealed complex patterns of synergy and antagonism. In conclusion, the work presented here offers important contributions and findings that may accelerate and/or improve different parts of the field of drug combination discovery and development.
|
|
| 23. |
- Kashif, Muhammad, et al.
(författare)
-
Structural and impedance spectroscopy study of Al-doped ZnO nanorods grown by sol-gel method
- 2012
-
Ingår i: Microelectronics international. - : Emerald. - 1356-5362 .- 1758-812X. ; 29:3, s. 131-135
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to investigate the electrical transport mechanism of the Al-doped ZnO nanorods at different temperatures by employing impedance spectroscopy. less thanbrgreater than less thanbrgreater thanDesign/methodology/approach - Al-doped ZnO nanorods were grown on silicon substrate using step sol-gel method. For the seed solution preparation Zinc acetate dihydrate, 2-methoxyethanol, monoethanolannine and aluminum nitrite nano-hydrate were used as a solute, solvent, stabilizer and dopant, respectively. Prior to the deposition, P-type Si (100) wafer was cut into pieces of 1 cm x 2 cm. The samples were then cleaned in an ultrasonic bath with acetone, ethanol, and de-ionized (DI) water for 5 min. The prepared seed solution was coated on silicon substrate using spin coater at spinning speed of 3000 rpm for 30s and then dried at 250 degrees C for 10 min followed by annealing at 550 degrees C for 1 h. The hydrothermal growth was carried out in a solution of zinc nitrate hexahydrate (0.025M), Hexamethyltetramine (0.025M) in DI water. less thanbrgreater than less thanbrgreater thanFindings - Al-doped ZnO nanorods were characterized using scanning electron microscope (SEM), X-ray diffraction (XRD) and impedance spectroscopy. The impedance measurements were carried out at various temperatures (100 degrees C-325 degrees C). The impedance results showed that temperature has great influence on the impedance; the impedance value decreased as the temperature increased. This decrement is attributed to the increase of the mobility of the defects, especially the oxygen vacancies. The surface morphology of the samples was measured by SEM and X-ray diffraction. The SEM images show that the high density of Al-doped ZnO nanorods covers the silicon substrate, whereas the XRD pattern shows the (002) crystal orientation. less thanbrgreater than less thanbrgreater thanOriginality/value - This paper demonstrates the electron transport mechanism of Al-doped ZnO nanorods, at different temperatures, to understand the charge transport model.
|
|
| 24. |
|
|
| 25. |
- Nadeem, Muhammad, et al.
(författare)
-
New generators for minimal circular generalised neighbour designs in blocks of two different sizes
- 2023
-
Ingår i: Statistics in Transition New Series. - 1234-7655 .- 2450-0291. ; 24:2, s. 85-92
-
Tidskriftsartikel (refereegranskat)abstract
- Minimal neighbour designs (NDs) are used when a response of a treatment (direct effect) is affected by the treatment(s) applied in the neighbouring units. Minimal generalised NDs are preferred when minimal NDs cannot be constructed. Through the method of cyclic shifts (Rule I), the conditions for the existence of minimal circular generalised NDs are discussed, in which v/2 unordered pairs do not appear as neighbours. Certain generators are also developed to obtain minimal circular generalised NDs in blocks of two different sizes, where k2 = 3, 4 and 5. All these designs are constructed using i sets of shifts for k1 and two for k2.
|
|
| 26. |
- Nahi, Hareth, et al.
(författare)
-
Minimal residual disease status is the prognostic determinant following high-dose treatment for patients with multiple myeloma
- 2023
-
Ingår i: Cancer Medicine. - : WILEY. - 2045-7634. ; 12:22, s. 20736-20744
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The presence of minimal residual disease (MRD+) following autologous stem cell transplantation (ASCT) in multiple myeloma represents a poor prognostic factor for progression-free survival (PFS) and overall survival (OS).Methods: At our department, we recommend lenalidomide maintenance for patients who are MRD+ after ASCT, while MRD-negative (MRD-) patients, after information about the national guidelines, were not advised to follow this regimen.Results: Out of the total 228 patients, 175 received ASCT following first-line induction (MRD- 92 (53%), MRD+ 83 (47%), at 2 months post-ASCT), while 53 underwent ASCT after second-line treatment (MRD- 27 (51%), MRD+ 26 (49%), at the same time point). Comparatively, MRD- patients who did not receive maintenance demonstrated better OS than MRD+ patients who received upfront ASCT and maintenance treatment (96% vs. 86%, p = 0.030, at 3 years). However, nonsignificant difference was found in PFS (76% vs. 62%, at 3 years). Furthermore, second-line ASCT, MRD- non-maintained patients exhibited significantly better PFS than MRD+ (71% vs. 27%, p > 0.001, at 3 years). However, OS was better but nonsignificant (96% vs. 76%, at 3 years). Fluorescence in situ hybridization (FISH) analysis was performed on 141 out of the 228 patients. Of these, 85 (60%) patients were deemed standard risk (SR), and 56 (40%) were classified as high risk (HR). In the SR cohort, MRD- patients exhibited better PFS and OS than MRD+ patients (71% vs. 59% and 100% vs. 85%, respectively). In the HR cohort, the MRD- patients showed superior PFS but similar OS compared to MRD+ patients (66% vs. 42% and 81% vs. 80%, respectively).Conclusions: Our results indicate that being MRD- is a more crucial prognostic factor for the 3-year PFS and OS than the presence of high-risk cytogenetic markers or undergoing maintenance treatment. The latter appears insufficient, particularly for MRD+ patients following ASCT in the second-line setting, suggesting that these patients may require a more intensive treatment approach.
|
|
| 27. |
- Riaz, Muhammad, et al.
(författare)
-
Construction of efficient classes of circular balanced repeated measurements designs with R
- 2024
-
Ingår i: Communications in Statistics - Theory and Methods. - 0361-0926 .- 1532-415X.
-
Tidskriftsartikel (refereegranskat)abstract
- Pharmacology, medicine, psychology, and the animal sciences all employ repeated measurement designs (RMDs). However, RMDs may experience carryover effects, which are the primary cause of bias in treatment effect estimation. In order to eliminate the carryover effects for odd v (the number of treatments), minimal circular balanced and strongly balanced repeated measurement designs (RMDs) are the ones that should be used. The minimal circular partially balanced and weakly balanced RMDs are used for even v. In order to obtain these important classes of minimal circular RMDs in periods of equal, two, and three different sizes, an R-based algorithm is developed in this article. The newly developed algorithm has made so simple the construction of balanced RMDs and their generalized classes. As a result, it is a novel piece of research.
|
|
| 28. |
- Saeed, Sajeel, et al.
(författare)
-
Impact of COVID-19 on palliative care of cancer patients : Perspectives from Pakistan
- 2022
-
Ingår i: Annals of Medicine and Surgery. - : Ovid Technologies (Wolters Kluwer Health). - 2049-0801. ; 78
-
Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has adversely affected the survival rate and palliative care of cancer patients all over the globe. In Pakistan, there are only a few institutions and organizations which provide specialized facilities for palliative care. During the pandemic, these specialized facilities were further limited. As only less than one percent of people had access to palliative care across Pakistan in the pandemic, the situation can be improved by establishing more such departments, providing telemedicine, increasing social media campaigns, and highlighting the importance of palliative care among cancer patients.
|
|
| 29. |
- Shahbaz, Muhammad, et al.
(författare)
-
Industrialization, electricity consumption and CO2 emissions in Bangladesh
- 2014
-
Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 31, s. 575-586
-
Forskningsöversikt (refereegranskat)abstract
- This paper investigates the relationship between industrialization, electricity consumption and CO2 emissions in case of Bangladesh using quarter frequency data over the period of 1975–2010. The ARDL bounds testing approach is applied to examine cointegration in the presence of structural breaks stemming in the series. The causal relationship among the variables is explored by applying the innovative accounting approach (IAA).Our results indicate that the variables are cointegrated for a long run relationship. We find that financial development adds in energy pollutants. Electricity consumption contributes to CO2 emissions. Trade openness also has a positive impact on energy pollutants. The results unveil that EKC is existed between industrial development and CO2 emissions in case of Bangladesh. Our causality analysis shows that electricity consumption Granger causes energy pollutants, industrial growth and financial development. The unidirectional causality exists running from financial development to trade openness and trade openness Granger causes industrial development. This study opens up new insights for policy makers in formulating a comprehensive economic, financial and trade policy to sustain industrialization by improving the environmental quality.
|
|
| 30. |
- Shibli, Muhammad Awais, et al.
(författare)
-
MagicNET : Secure communication methodology for mobile agents
- 2010
-
Ingår i: The 12th International Conference on Advanced Communication Technology. - 9788955191455 ; , s. 1567-1573
-
Konferensbidrag (refereegranskat)abstract
- Most of the current research and development results, dealing with authentication of mobile agents, describe solutions that address only agent-to-platform authentication. These solutions assign privileges to agents so that they can be executed and then, by using the same privileges, also to communicate with other agents running on the same platform. They do not address broader agent-to-agent communication security requirements. Moreover, communication protocols are not based on any standards, what increases the possibilities of communications between benign and malicious agents. In this paper we describe agent-to-agent secure communication methodology that guarantees authenticated, authorized and confidential communication between agents. We use FIPA ACL standard for effective and interoperable communication in our agent-based system.
|
|
| 31. |
- Usman Ali, Syed, et al.
(författare)
-
A Potentiometric Indirect Uric Acid Sensor Based on ZnO Nanoflakes and Immobilized Uricase
- 2012
-
Ingår i: Sensors. - : MDPI. - 1424-8220. ; 12:3, s. 2787-2797
-
Tidskriftsartikel (refereegranskat)abstract
- In the present work zinc oxide nanoflakes (ZnO-NF) structures with a wall thickness around 50 to 100 nm were synthesized on a gold coated glass substrate using a low temperature hydrothermal method. The enzyme uricase was electrostatically immobilized in conjunction with Nafion membrane on the surface of well oriented ZnO-NFs, resulting in a sensitive, selective, stable and reproducible uric acid sensor. The electrochemical response of the ZnO-NF-based sensor vs. a Ag/AgCl reference electrode was found to be linear over a relatively wide logarithmic concentration range (500 nM to 1.5 mM). In addition, the ZnO-NF structures demonstrate vast surface area that allow high enzyme loading which results provided a higher sensitivity. The proposed ZnO-NF array-based sensor exhibited a high sensitivity of similar to 66 mV/ decade in test electrolyte solutions of uric acid, with fast response time. The sensor response was unaffected by normal concentrations of common interferents such as ascorbic acid, glucose, and urea.
|
|
| 32. |
- Usman, Muhammad, et al.
(författare)
-
Evaluation of the chronic intoxication of fluoride on human serum metabolome using untargeted metabolomics
- 2022
-
Ingår i: Arabian Journal of Chemistry. - : Elsevier BV. - 1878-5352 .- 1878-5379. ; 15:7
-
Tidskriftsartikel (refereegranskat)abstract
- Drinking water is the main source of fluoride intake for the human body and its regulated consumption helps in decreasing dental caries. However, excessive fluoride consumption over a prolonged time period causes fluorosis disease which adversely affects many tissues and organs of the body. This paper describes the evaluation of chronic intoxication of fluoride on human serum metabolome. The untargeted metabolomics approach using UPLC-QTOF-MS/MS is applied for metabolomic profiling, whereas the estimation of fluoride in serum samples was carried out using the ion-selective electrode (ISE). Fluoride concentration was found to be 0.16–1.25 mg/L in serum samples of 39 fluorosis patients and 0.008–0.045 mg/L in 20 healthy samples. A total of 47 metabolites were identified based on the high-resolution mass spectrometry analysis. A volcano plot was generated to discriminate features that are significantly different between the fluorosis and healthy groups at the probability of 0.05 and fold change ≥ 2. Among all identified metabolites, intensities of ten differential identified metabolites including inosine, α-linolenic acid, guanosine, octanoyl-L-carnitine, His-Trp, phytosphingosine, lauroyl-L-carnitine, hydrocortisone, deoxyinosine and dodecanedioic acid have been found altered in disease samples compared to healthy controls. Major pathways identified based on these metabolites include energy metabolism, fatty acid oxidation, purine degradation pathway, elevated protein degradation, and increased ω-6 fatty acid linoleate signatures were observed.
|
|
| 33. |
- Österroos, Albin, et al.
(författare)
-
Combination screening in vitro identifies synergistically acting KP372-1 and cytarabine against acute myeloid leukemia
- 2016
-
Ingår i: Biochemical Pharmacology. - : Elsevier BV. - 0006-2952 .- 1356-1839. ; 118, s. 40-49
-
Tidskriftsartikel (refereegranskat)abstract
- Cytogenetic lesions often alter kinase signaling in acute myeloid leukemia (AML) and the addition of kinase inhibitors to the treatment arsenal is of interest. We have screened a kinase inhibitor library and performed combination testing to find promising drug-combinations for synergistic killing of AML cells. Cytotoxicity of 160 compounds in the library InhibitorSelect (TM) 384-Well Protein Kinase Inhibitor I was measured using the fluorometric microculture cytotoxicity assay (FMCA) in three AML cell lines. The 15 most potent substances were evaluated for dose-response. The 6 most cytotoxic compounds underwent combination synergy analysis based on the FMCA readouts after either simultaneous or sequential drug addition in AML cell lines. The 4 combinations showing the highest level of synergy were evaluated in 5 primary AML samples. Synergistic calculations were performed using the combination interaction analysis package COMBIA, written in R, using the Bliss independence model. Based on obtained results, an iterative combination search was performed using the therapeutic algorithmic combinatorial screen (TACS) algorithm. Of 160 substances, cell survival was <= 50% at <0.5 mu M for Cdk/Crk inhibitor, KP372-1, synthetic fascaplysin, herbimycin A, PDGF receptor tyrosine kinase inhibitor IV and reference-drug cytarabine. KP372-1, synthetic fascaplysin or herbimycin A obtained synergy when combined with cytarabine in AML cell lines MV4-11 and HL-60. KP372-1 added 24 h before cytarabine gave similar results in patient cells. The iterative search gave further improved synergy between cytarabine and KP372-1. In conclusion, our in vitro studies suggest that combining KP372-1 and cytarabine is a potent and synergistic drug combination in AML.
|
|
