Displaying publications 1 - 20 of 28 in total

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  1. Paste Aging Spontaneously Tunes TiO2 Nanoparticles into Reproducible Electrosprayed Photoelectrodes
    Shahiduzzaman M, Chen B, Akhtaruzzaman M, Wang L, Fukuhara H, Tomita K, et al.
    ACS Appl Mater Interfaces, 2021 Nov 17;13(45):53758-53766.
    PMID: 34735118 DOI: 10.1021/acsami.1c13793
    In this study, the spontaneous microstructure tuning of TiO2 was observed by aging the ethanol/water TiO2 paste for up to 20 days at ambient conditions. A dynamic light scattering study reveals that it formed the outstanding reproducible TiO2 microstructure with a ∼200 nm average particle size and stabilizes in 6 to 20 days under an ambient atmosphere. Interestingly, the as-deposited day 15 sample spontaneously changed its crystallinity upon keeping the paste at ambient conditions; meanwhile the day 0 sample showed an amorphous structure. A dense, uniform, and stable TiO2 electrode was cast on a fluorine doped-tin oxide substrate using the electrospray technique. We exploit the spontaneous evolution of the TiO2 nanopowder to revisit the fabrication procedure of the TiO2 photoelectrode for dye-sensitized solar cells (DSSCs). The controlled microstructure TiO2 film was used in DSSCs, which, to the best of our knowledge, achieved the highest power conversion efficiency of 9.65% using N719 dye in sensitizing the TiO2 photoanode.
  2. Fulltext Recovery of FTO coated glass substrate via environment-friendly facile recycling perovskite solar cells
    Chowdhury MS, Rahman KS, Selvanathan V, Hasan AKM, Jamal MS, Samsudin NA, et al.
    RSC Adv, 2021 Apr 15;11(24):14534-14541.
    PMID: 35423997 DOI: 10.1039/d1ra00338k
    Organic-inorganic perovskite solar cells (PSCs) have recently emerged as a potential candidate for large-scale and low-cost photovoltaic devices. However, the technology is still susceptible to degradation issues and toxicity concerns due to the presence of lead (Pb). Therefore, investigation on ideal methods to deal with PSC wastes once the device attains its end-of-life is crucial and to recycle the components within the cell is the most cost effective and energy effective method by far. This paper reported on a layer-by-layer extraction approach to recycle the fluorine-doped tin oxide (FTO) coated glass substrate which is the most expensive component in the device architecture of mesoporous planar PSC. By adapting the sequential removal of each layer, chemical properties of individual components, including spiro-OMeTAD and gold can be preserved, enabling the material to be easily reused. It also ensured that the toxic Pb component could be isolated without contaminating other materials. The removal of all individual layers allows the retrieval of FTO conductive glass which can be used in various applications that are not only restricted to photovoltaics. Comparison of electrical, morphological and physical properties of recycled FTO glasses to commercial ones revealed minimal variations. This confirmed that the recycling approach was useful in retrieving the substrate without affecting its physicochemical properties.
  3. Fulltext Metal Oxide Compact Electron Transport Layer Modification for Efficient and Stable Perovskite Solar Cells
    Shahiduzzaman M, Fukaya S, Muslih EY, Wang L, Nakano M, Akhtaruzzaman M, et al.
    Materials (Basel), 2020 May 11;13(9).
    PMID: 32403454 DOI: 10.3390/ma13092207
    Perovskite solar cells (PSCs) have appeared as a promising design for next-generation thin-film photovoltaics because of their cost-efficient fabrication processes and excellent optoelectronic properties. However, PSCs containing a metal oxide compact layer (CL) suffer from poor long-term stability and performance. The quality of the underlying substrate strongly influences the growth of the perovskite layer. In turn, the perovskite film quality directly affects the efficiency and stability of the resultant PSCs. Thus, substrate modification with metal oxide CLs to produce highly efficient and stable PSCs has drawn attention. In this review, metal oxide-based electron transport layers (ETLs) used in PSCs and their systemic modification are reviewed. The roles of ETLs in the design and fabrication of efficient and stable PSCs are also discussed. This review will guide the further development of perovskite films with larger grains, higher crystallinity, and more homogeneous morphology, which correlate to higher stable PSC performance. The challenges and future research directions for PSCs containing compact ETLs are also described with the goal of improving their sustainability to reach new heights of clean energy production.
  4. Fulltext Tetraalkylammonium salts (TAS) in solar energy applications - A review on in vitro and in vivo toxicity
    Mustafa NM, Jumaah FN, Ludin NA, Akhtaruzzaman M, Hassan NH, Ahmad A, et al.
    Heliyon, 2024 Apr 15;10(7):e27381.
    PMID: 38560257 DOI: 10.1016/j.heliyon.2024.e27381
    Tetraalkylammonium salt (TAS) is an organic salt widely employed as a precursor, additive or electrolyte in solar cell applications, such as perovskite or dye-sensitized solar cells. Notably, Perovskite solar cells (PSCs) have garnered acclaim for their exceptional efficiency. However, PSCs have been associated with environmental and health concerns due to the presence of lead (Pb) content, the use of hazardous solvents, and the incorporation of TAS in their fabrication processes, which significantly contributes to environmental and human health toxicity. As a response, there is a growing trend towards transitioning to safer and biobased materials in PSC fabrication to address these concerns. However, the potential health hazards associated with TAS necessitate a thorough evaluation, considering the widespread use of this substance. Nevertheless, the overexploitation of TAS could potentially increase the disposal of TAS in the ecosystem, thus, posing a major health risk and severe pollution. Therefore, this review article presents a comprehensive discussion on the in vitro and in vivo toxicity assays of TAS as a potential material in solar energy applications, including cytotoxicity, genotoxicity, in vivo dermal, and systemic toxicity. In addition, this review emphasizes the toxicity of TAS compounds, particularly the linear tetraalkyl chain structures, and summarizes essential findings from past studies as a point of reference for the development of non-toxic and environmentally friendly TAS derivatives in future studies. The effects of the TAS alkyl chain length, polar head and hydrophobicity, cation and anion, and other properties are also included in this review.
  5. Impact of Ar Flow Rates on Micro-Structural Properties of WS2 Thin Film by RF Magnetron Sputtering
    Akhtaruzzaman M, Shahiduzzaman M, Amin N, Muhammad G, Islam MA, Rafiq KSB, et al.
    Nanomaterials (Basel), 2021 Jun 22;11(7).
    PMID: 34206518 DOI: 10.3390/nano11071635
    Tungsten disulfide (WS2) thin films were deposited on soda-lime glass (SLG) substrates using radio frequency (RF) magnetron sputtering at different Ar flow rates (3 to 7 sccm). The effect of Ar flow rates on the structural, morphology, and electrical properties of the WS2 thin films was investigated thoroughly. Structural analysis exhibited that all the as-grown films showed the highest peak at (101) plane corresponds to rhombohedral phase. The crystalline size of the film ranged from 11.2 to 35.6 nm, while dislocation density ranged from 7.8 × 1014 to 26.29 × 1015 lines/m2. All these findings indicate that as-grown WS2 films are induced with various degrees of defects, which were visible in the FESEM images. FESEM images also identified the distorted crystallographic structure for all the films except the film deposited at 5 sccm of Ar gas flow rate. EDX analysis found that all the films were having a sulfur deficit and suggested that WS2 thin film bears edge defects in its structure. Further, electrical analysis confirms that tailoring of structural defects in WS2 thin film can be possible by the varying Ar gas flow rates. All these findings articulate that Ar gas flow rate is one of the important process parameters in RF magnetron sputtering that could affect the morphology, electrical properties, and structural properties of WS2 thin film. Finally, the simulation study validates the experimental results and encourages the use of WS2 as a buffer layer of CdTe-based solar cells.
  6. Enhanced Photovoltaic Performances of Dye-Sensitized Solar Cells by Co-Sensitization of Benzothiadiazole and Squaraine-Based Dyes
    Islam A, Akhtaruzzaman M, Chowdhury TH, Qin C, Han L, Bedja IM, et al.
    ACS Appl Mater Interfaces, 2016 Feb;8(7):4616-23.
    PMID: 26812212 DOI: 10.1021/acsami.5b11134
    Dye-sensitized solar cells (DSSCs) based on a donor-acceptor-donor oligothienylene dye containing benzothiadiazole (T4BTD-A) were cosensitized with dyes containing cis-configured squaraine rings (HSQ3 and HSQ4). The cosensitized dyes showed incident monochromatic photon-to-current conversion efficiency (IPCE) greater than 70% in the 300-850 nm wavelength region. The individual overall conversion efficiencies of the sensitizers T4BTD-A, HSQ3, and HSQ4 were 6.4%, 4.8%, and 5.8%, respectively. Improved power conversion efficiencies of 7.0% and 7.7% were observed when T4BTD-A was cosensitized with HSQ3 and HSQ4, respectively, thanks to a significant increase in current density (JSC) for the cosensitized DSSCs. Intensity-modulated photovoltage spectroscopy results showed a longer lifetime for cosensitized T4BTD-A+HSQ3 and T4BTD-A+HSQ4 compared to that of HSQ3 and HSQ4, respectively.
  7. Fulltext A comprehensive photovoltaic study on tungsten disulfide (WS2) buffer layer based CdTe solar cell
    Emon EI, Islam AM, Sobayel MK, Islam S, Akhtaruzzaman M, Amin N, et al.
    Heliyon, 2023 Mar;9(3):e14438.
    PMID: 36950573 DOI: 10.1016/j.heliyon.2023.e14438
    Transition metal di-chalcogenides (TMCDs)-Tungsten disulfide (WS2) exhibit excellent optoelectronic properties such as suitable bandgap, high absorption coefficient, good conductivity, high carrier mobility, etc. to be used as a photovoltaic material for thin-film solar cells. In the present work, we have replaced the traditional buffer CdS and ITO/ZnO window layer in CdTe solar cells with the non-toxic, earth-abundant WS2 buffer and SnO2 window layer, respectively. The SCAPS-1D solar simulator is used to investigate the potentiality of WS2 as buffer material in CdTe solar cells. This numerical study provides a comparison of the performances between the proposed structure: SnO2/WS2/CdTe/Au and the baseline structure: ITO/ZnO/CdS/CdTe/Au. The impacts of the charge carrier generation rate, spectral response, current-voltage characteristics, bulk defect density, defect density at buffer/absorber interface, operating temperature, and capacitance-voltage characteristics on the solar cell performance parameters have also been analyzed. The tolerance level of defect density in WS2 bulk and WS2/CdTe interface are found to be 1017 cm-3 and 1012 cm-3, respectively. The temperature study reveals the poor structural robustness and thermal stability of the proposed cell. The conversion efficiency of the proposed cell has found to be 20.55% at the optimized device structure. Nevertheles, these findings may provide an insight to fabricate viable, environment friendly, and inexpensive CdTe thin-film solar cells.
  8. Fulltext Transformation of Oil Palm Waste-Derived Cellulose into Solid Polymer Electrolytes: Investigating the Crucial Role of Plasticizers
    Abouloula CN, Rizwan M, Selvanathan V, Yahya R, Althubeiti K, Alkhammash HI, et al.
    Polymers (Basel), 2021 Oct 26;13(21).
    PMID: 34771242 DOI: 10.3390/polym13213685
    This study explores the possibility of transforming lignocellulose-rich agricultural waste materials into value-added products. Cellulose was extracted from an empty fruit bunch of oil palm and further modified into carboxymethyl cellulose (CMC), a water-soluble cellulose derivative. The CMC was then employed as the polymeric content in fabrication of solid polymer electrolyte (SPE) films incorporated with lithium iodide. To enhance the ionic conductivity of the solid polymer electrolytes, the compositions were optimized with different amounts of glycerol as a plasticizing agent. The chemical and physical effects of plasticizer content on the film composition were studied by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) analysis. FTIR and XRD analysis confirmed the interaction plasticizer with the polymer matrix and the amorphous nature of fabricated SPEs. The highest ionic conductivity of 6.26 × 10-2 S/cm was obtained with the addition of 25 wt % of glycerol. By fabricating solid polymer electrolytes from oil palm waste-derived cellulose, the sustainability of the materials can be retained while reducing the dependence on fossil fuel-derived materials in electrochemical devices.
  9. Airborne particles in the city center of Kuala Lumpur: Origin, potential driving factors, and deposition flux in human respiratory airways
    Khan MF, Hamid AH, Bari MA, Tajudin ABA, Latif MT, Nadzir MSM, et al.
    Sci Total Environ, 2019 Feb 10;650(Pt 1):1195-1206.
    PMID: 30308807 DOI: 10.1016/j.scitotenv.2018.09.072
    Equatorial warming conditions in urban areas can influence the particle number concentrations (PNCs), but studies assessing such factors are limited. The aim of this study was to evaluate the level of size-resolved PNCs, their potential deposition rate in the human respiratory system, and probable local and transboundary inputs of PNCs in Kuala Lumpur. Particle size distributions of a 0.34 to 9.02 μm optical-equivalent size range were monitored at a frequency of 60 s between December 2016 and January 2017 using an optical-based compact scanning mobility particle sizer (SMPS). Diurnal and correlation analysis showed that traffic emissions and meteorological confounding factors were potential driving factors for changes in the PNCs (Dp ≤1 μm) at the modeling site. Trajectory modeling showed that a PNC <100/cm3 was influenced mainly by Indo-China region air masses. On the other hand, a PNC >100/cm3 was influenced by air masses originating from the Indian Ocean and Indochina regions. Receptor models extracted five potential sources of PNCs: industrial emissions, transportation, aged traffic emissions, miscellaneous sources, and a source of secondary origin coupled with meteorological factors. A respiratory deposition model for male and female receptors predicted that the deposition flux of PM1 (particle mass ≤1 μm) into the alveolar (AL) region was higher (0.30 and 0.25 μg/h, respectively) than the upper airway (UA) (0.29 and 0.24 μg/h, respectively) and tracheobronchial (TB) regions (0.02 μg/h for each). However, the PM2.5 deposition flux was higher in the UA (2.02 and 1.68 μg/h, respectively) than in the TB (0.18 and 0.15 μg/h, respectively) and the AL regions (1.09 and 0.91 μg/h, respectively); a similar pattern was also observed for PM10.
  10. Fulltext Provision of renal-specific nutrition knowledge for changing dietary practice in Bangladeshi hemodialysis patients
    Rahman T, Ahmed S, Kabir MR, Akhtaruzzaman M, Mitali EJ, Rashid HU, et al.
    PEC Innov, 2022 Dec;1:100028.
    PMID: 37213733 DOI: 10.1016/j.pecinn.2022.100028
    OBJECTIVE: Studies show that provision of nutrition knowledge help renal patients make informed food choices. This study aimed to evaluate the impact of nutrition knowledge for changing dietary practice among Bangladeshi dialysis patients.

    METHODS: Following development of a renal-specific nutrition booklet, a pilot study was conducted among 50 hemodialysis patients from a single dialysis setting. Demographic, anthropometric, clinical, biochemical, dietary data, and a 10-item MCQ on renal-specific nutrition information were collected before and 3 months after the provision of the booklet.

    RESULTS: 52% of the participants were male, 54% had twice weekly dialysis, age 53 ± 12 years, and dialysis vintage was 46 ± 25 months. Serum potassium and phosphorous, dietary potassium, phosphorous, and phosphorous to protein ratio were significantly reduced after the provision of the booklet. Additionally, patients consuming >3 meals/day increased to 66% while adherence to renal-specific cooking method and vegetable preference were significantly increased to 70% and 62%, respectively.

    CONCLUSION: Provision of knowledge via renal-specific nutrition booklet was able to improve patients' dietary practice and enhance their dietary adherence to renal specific recommendations.

    INNOVATION: The booklet was developed using locally available food items in local language and was found beneficial in low-resource settings where overall health care facilities, including nutrition support are limited.

  11. Fulltext Spray Pyrolyzed TiO2 Embedded Multi-Layer Front Contact Design for High-Efficiency Perovskite Solar Cells
    Shahiduzzaman M, Hossain MI, Visal S, Kaneko T, Qarony W, Umezu S, et al.
    Nanomicro Lett, 2021 Jan 04;13(1):36.
    PMID: 34138244 DOI: 10.1007/s40820-020-00559-2
    The photovoltaic performance of perovskite solar cells (PSCs) can be improved by utilizing efficient front contact. However, it has always been a significant challenge for fabricating high-quality, scalable, controllable, and cost-effective front contact. This study proposes a realistic multi-layer front contact design to realize efficient single-junction PSCs and perovskite/perovskite tandem solar cells (TSCs). As a critical part of the front contact, we prepared a highly compact titanium oxide (TiO2) film by industrially viable Spray Pyrolysis Deposition (SPD), which acts as a potential electron transport layer (ETL) for the fabrication of PSCs. Optimization and reproducibility of the TiO2 ETL were discreetly investigated while fabricating a set of planar PSCs. As the front contact has a significant influence on the optoelectronic properties of PSCs, hence, we investigated the optics and electrical effects of PSCs by three-dimensional (3D) finite-difference time-domain (FDTD) and finite element method (FEM) rigorous simulations. The investigation allows us to compare experimental results with the outcome from simulations. Furthermore, an optimized single-junction PSC is designed to enhance the energy conversion efficiency (ECE) by > 30% compared to the planar reference PSC. Finally, the study has been progressed to the realization of all-perovskite TSC that can reach the ECE, exceeding 30%. Detailed guidance for the completion of high-performance PSCs is provided.
  12. Optimization of a high-performance lead-free cesium-based inorganic perovskite solar cell through numerical approach
    Tulka TK, Alam N, Akhtaruzzaman M, Sobayel K, Hossain MM
    Heliyon, 2022 Nov;8(11):e11719.
    PMID: 36425430 DOI: 10.1016/j.heliyon.2022.e11719
    In this work, an ultra-thin (0.815 μm) lead-free all-inorganic novel PV cell structure consisting of solid-state layers with the configuration SnO2/ZnOS/CsGeI3/CZTSe/Au has been optimized using SCAPS-1D simulator. ZnOS electron transport layer (ETL) has been deployed and various hole transport layer (HTL) material candidates have been considered to find the most suitable one in order to get the maximum possible power conversion efficiency (PCE). The simulation begins with the optimization of the thickness of the ZnOS buffer layer, followed by an analysis of HTL and ETL doping concentrations, thickness and bandgap optimization of absorber layer. The maximum permissible defect density at the ZnOS/CsGeI3 interface and the bulk defect density of the absorber layer (CsGeI3) are also investigated. It is also found that when the temperature rises, short circuit current density (J sc ) rises by 1.43 mA/K and open-circuit voltage (V oc ) degrades by 2 mV/K. The optimized structure results in a PCE of 26.893% with J sc , V oc , and fill factor (FF) of 28.172 mA cm-2, 1.0834 V, and 88.107% respectively. The cell performance parameters outperform those found in the recent literature. The simulated results of the proposed configuration are expected to be a helpful reference for the future implementation of a cost-effective and efficient all-inorganic perovskite PV cell.
  13. Fulltext Degradation of Perovskite Thin Films and Solar Cells with Candle Soot C/Ag Electrode Exposed in a Control Ambient
    Islam MA, Mohafez H, Sobayel K, Wan Muhamad Hatta SF, Hasan AKM, Khandaker MU, et al.
    Nanomaterials (Basel), 2021 Dec 20;11(12).
    PMID: 34947812 DOI: 10.3390/nano11123463
    Perovskite solar cells (PSCs) have already achieved efficiencies of over 25%; however, their instability and degradation in the operational environment have prevented them from becoming commercially viable. Understanding the degradation mechanism, as well as improving the fabrication technique for achieving high-quality perovskite films, is crucial to overcoming these shortcomings. In this study, we investigated details in the changes of physical properties associated with the degradation and/or decomposition of perovskite films and solar cells using XRD, FESEM, EDX, UV-Vis, Hall-effect, and current-voltage (I-V) measurement techniques. The dissociation, as well as the intensity of perovskite peaks, have been observed as an impact of film degradation by humidity. The decomposition rate of perovskite film has been estimated from the structural and optical changes. The performance degradation of novel planner structure PSCs has been investigated in detail. The PSCs were fabricated in-room ambient using candle soot carbon and screen-printed Ag electrode. It was found that until the perovskite film decomposed by 30%, the film properties and cell efficiency remained stable.
  14. Prospects of Graphene as a Potential Carrier-Transport Material in Third-Generation Solar Cells
    Chowdhury TH, Islam A, Mahmud Hasan AK, Terdi MA, Arunakumari M, Prakash Singh S, et al.
    Chem Rec, 2016 Apr;16(2):614-32.
    PMID: 26816190 DOI: 10.1002/tcr.201500206
    Third-generation solar cells are understood to be the pathway to overcoming the issues and drawbacks of the existing solar cell technologies. Since the introduction of graphene in solar cells, it has been providing attractive properties for the next generation of solar cells. Currently, there are more theoretical predictions rather than practical recognitions in third-generation solar cells. Some of the potential of graphene has been explored in organic photovoltaics (OPVs) and dye-sensitized solar cells (DSSCs), but it has yet to be fully comprehended in the recent third-generation inorganic-organic hybrid perovskite solar cells. In this review, the diverse role of graphene in third-generation OPVs and DSSCs will be deliberated to provide an insight on the prospects and challenges of graphene in inorganic-organic hybrid perovskite solar cells.
  15. Fulltext WS2: A New Window Layer Material for Solar Cell Application
    Bin Rafiq MKS, Amin N, Alharbi HF, Luqman M, Ayob A, Alharthi YS, et al.
    Sci Rep, 2020 Jan 21;10(1):771.
    PMID: 31964954 DOI: 10.1038/s41598-020-57596-5
    Radio frequency (RF) magnetron sputtering was used to deposit tungsten disulfide (WS2) thin films on top of soda lime glass substrates. The deposition power of RF magnetron sputtering varied at 50, 100, 150, 200, and 250 W to investigate the impact on film characteristics and determine the optimized conditions for suitable application in thin-film solar cells. Morphological, structural, and opto-electronic properties of as-grown films were investigated and analyzed for different deposition powers. All the WS2 films exhibited granular morphology and consisted of a rhombohedral phase with a strong preferential orientation toward the (101) crystal plane. Polycrystalline ultra-thin WS2 films with bandgap of 2.2 eV, carrier concentration of 1.01 × 1019 cm-3, and resistivity of 0.135 Ω-cm were successfully achieved at RF deposition power of 200 W. The optimized WS2 thin film was successfully incorporated as a window layer for the first time in CdTe/WS2 solar cell. Initial investigations revealed that the newly incorporated WS2 window layer in CdTe solar cell demonstrated photovoltaic conversion efficiency of 1.2% with Voc of 379 mV, Jsc of 11.5 mA/cm2, and FF of 27.1%. This study paves the way for WS2 thin film as a potential window layer to be used in thin-film solar cells.
  16. Fulltext In vitro antioxidant activity of Ficus carica L. latex from 18 different cultivars
    Shahinuzzaman M, Yaakob Z, Anuar FH, Akhtar P, Kadir NHA, Hasan AKM, et al.
    Sci Rep, 2020 07 02;10(1):10852.
    PMID: 32616768 DOI: 10.1038/s41598-020-67765-1
    As synthetic antioxidants that are widely used in foods are known to cause detrimental health effects, studies on natural additives as potential antioxidants are becoming increasingly important. In this work, the total phenolic content (TPC) and antioxidant activity of Ficus carica Linn latex from 18 cultivars were investigated. The TPC of latex was calculated using the Folin-Ciocalteu assay. 1,1-Diphenyl-2-picrylhydrazyl (DPPH), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ferric ion reducing antioxidant power (FRAP) were used for antioxidant activity assessment. The bioactive compounds from F. carica latex were extracted via maceration and ultrasound-assisted extraction (UAE) with 75% ethanol as solvent. Under the same extraction conditions, the latex of cultivar 'White Genoa' showed the highest antioxidant activity of 65.91% ± 1.73% and 61.07% ± 1.65% in DPPH, 98.96% ± 1.06% and 83.04% ± 2.16% in ABTS, and 27.08 ± 0.34 and 24.94 ± 0.84 mg TE/g latex in FRAP assay via maceration and UAE, respectively. The TPC of 'White Genoa' was 315.26 ± 6.14 and 298.52 ± 9.20 µg GAE/mL via the two extraction methods, respectively. The overall results of this work showed that F. carica latex is a potential natural source of antioxidants. This finding is useful for further advancements in the fields of food supplements, food additives and drug synthesis in the future.
  17. Fulltext Electromagnetic Performances Analysis of an Ultra-wideband and Flexible Material Antenna in Microwave Breast Imaging: To Implement A Wearable Medical Bra
    Rahman A, Islam MT, Singh MJ, Kibria S, Akhtaruzzaman M
    Sci Rep, 2016 12 23;6:38906.
    PMID: 28008923 DOI: 10.1038/srep38906
    In this paper, we report a compact and ultra-wide band antenna on a flexible substrate using the 5-(4-(perfluorohexyl)phenyl)thiophene-2-carbaldehyde compound for microwave imaging. In contrast to other microwave based imaging systems, such as an array of 16 antennas, we proposed a bi-static radar based imaging system consisting of two omnidirectional antennas, which reduces complexity and the overall dimension. The proposed compact antennas are 20 × 14 mm2 and designed for operating at frequencies from 4 to 6 GHz. To allow for implantation into a bra, the electromagnetic performances of the antennas must be considered in bending conditions. In comparison with the recently reported flexible antennas, we demonstrated both electromagnetic performance and imaging reconstruction for bending conditions. For the proof of concept, the electromagnetic performances both at flat and bending conditions have been verified using a homogeneous multilayer model of the human breast phantom. Our results demonstrate that the antenna, even at bending conditions, exhibits an excellent omni-directional radiation pattern with an average efficiency above 70% and average gain above 1 dBi, within the operational frequency band. The comprehensive aim of the realized antenna is to design a biodegradable and wearable antenna-based bra for early breast cancer detection in the future.
  18. Fulltext Muntingia calabura Leaves Mediated Green Synthesis of CuO Nanorods: Exploiting Phytochemicals for Unique Morphology
    Selvanathan V, Aminuzzaman M, Tey LH, Razali SA, Althubeiti K, Alkhammash HI, et al.
    Materials (Basel), 2021 Oct 25;14(21).
    PMID: 34771914 DOI: 10.3390/ma14216379
    In this study, phytochemical assisted nanoparticle synthesis was performed using Muntingia calabura leaf extracts to produce copper oxide nanoparticles (CuO NPs) with interesting morphology. Scanning electron microscope (SEM) and transmission electron microscope (TEM) analysis of the biosynthesized CuO NPs reveal formation of distinct, homogeneous, and uniform sized CuO nanorods structure with thickness and length of around 23 nm and 79 nm, respectively. Based on Fourier-transform infrared (FTIR) analysis, the unique combinations of secondary metabolites such as flavonoid and polyphenols in the plant extract are deduced to be effective capping agents to produce nanoparticles with unique morphologies similar to conventional chemical synthesis. X-ray diffraction (XRD) analysis verified the monoclinical, crystalline structure of the CuO NPs. The phase purity and chemical identity of the product was consolidated via X-Ray photoelectron spectroscopy (XPS) and Raman spectroscopic data which indicate the formation of a single phase CuO without the presence of other impurities. The direct and indirect optical band gap energies of the CuO nanorods were recorded to be 3.65 eV and 1.42 eV.
  19. Fulltext Preparation and Characterization of Flexible Substrate Material from Phenyl-Thiophene-2-Carbaldehyde Compound
    Rahman A, Islam MT, Samsuzzaman M, Singh MJ, Akhtaruzzaman M
    Materials (Basel), 2016 May 11;9(5).
    PMID: 28773479 DOI: 10.3390/ma9050358
    In this paper, a novel phenyl-thiophene-2-carbaldehyde compound-based flexible substrate material has been presented. Optical and microwave characterization of the proposed material are done to confirm the applicability of the proposed material as a substrate. The results obtained in this work show that the phenyl-thiophene-2-carbaldehyde consists of a dielectric constant of 3.03, loss tangent of 0.003, and an optical bandgap of 3.24 eV. The proposed material is analyzed using commercially available EM simulation software and validated by the experimental analysis of the flexible substrate. The fabricated substrate also shows significant mechanical flexibility and light weight. The radiating copper patch deposited on the proposed material substrate incorporated with partial ground plane and microstrip feeding technique shows an effective impedance bandwidth of 3.8 GHz. It also confirms an averaged radiation efficiency of 81% throughout the frequency band of 5.4-9.2 GHz.
  20. Local and transboundary factors' impacts on trace gases and aerosol during haze episode in 2015 El Niño in Malaysia
    Samsuddin NAC, Khan MF, Maulud KNA, Hamid AH, Munna FT, Rahim MAA, et al.
    Sci Total Environ, 2018 Jul 15;630:1502-1514.
    PMID: 29554768 DOI: 10.1016/j.scitotenv.2018.02.289
    Southeast Asian haze is a semi-natural phenomenon that chokes the region each year during the dry monsoon season. Smoke-haze episodes caused by the vegetation and peat fires in Indonesia severely affected large parts of Malaysia during the 2015 El Niño phenomenon. This study aimed to evaluate the factors that influenced the concentrations of aerosol and trace gases during the 2015 haze and non-haze period on a semi-urban site in the southern part of Malaysian peninsula that facing Sumatra (Muar, Site A), and on an urban site near to Kuala Lumpur, influenced by the city centre (Cheras, Site B). Local land use data and the cluster of air mass weighted backward trajectory were used to identify the potential factors from local sources and the transboundary region, respectively. The annual median concentrations of PM10 for semi-urban and urban sites were 45.0μg/m3 and 47.0μg/m3, respectively for the study period (Jan-Dec 2015) from the hourly observation dataset. The highest PM10 concentrations during the haze were 358μg/m3 and 415μg/m3 for the two sites, respectively, representing absolutely unhealthy air. However, the trace gases were within the safe threshold. The average concentrations of PM10 and carbon monoxide were two fold higher during the haze than the non-haze episodes on both sites. Nitrogen dioxide was more influenced by haze compared with sulphur dioxide and ozone. The results of the land use change suggest that the local factor can also partially affect the air pollution on the urban area (Site B) but more visible in 2015. The results of the backward trajectory and the wildfire radiative power showed that the smoke-haze episodes that affected Malaysia in 2015 were mainly initiated in the Indonesian Sumatra and Kalimantan regions. This study provides a very useful information towards the impacted region during El Niño haze episode.
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