Browse publications by year: 2020

  1. Fulltext Biological remediation of acid mine drainage: Review of past trends and current outlook
    Rambabu K, Banat F, Pham QM, Ho SH, Ren NQ, Show PL
    Environ Sci Ecotechnol, 2020 Apr;2:100024.
    PMID: 36160925 DOI: 10.1016/j.ese.2020.100024
    Formation of acid mine drainage (AMD) is a widespread environmental issue that has not subsided throughout decades of continuing research. Highly acidic and highly concentrated metallic streams are characteristics of such streams. Humans, plants and surrounding ecosystems that are in proximity to AMD producing sites face immediate threats. Remediation options include active and passive biological treatments which are markedly different in many aspects. Sulfate reducing bacteria (SRB) remove sulfate and heavy metals to generate non-toxic streams. Passive systems are inexpensive to operate but entail fundamental drawbacks such as large land requirements and prolonged treatment period. Active bioreactors offer greater operational predictability and quicker treatment time but require higher investment costs and wide scale usage is limited by lack of expertise. Recent advancements include the use of renewable raw materials for AMD clean up purposes, which will likely achieve much greener mitigation solutions.
  2. Fulltext Docking and in vitro molecular biology studies of p-anisidine-appended 1-hydroxy-2-acetonapthanone Schiff base lanthanum(iii) complexes
    Sathiyanarayanan V, Prasath PV, Sekhar PC, Ravichandran K, Easwaramoorthy D, Mohammad F, et al.
    RSC Adv, 2020 Apr 23;10(28):16457-16472.
    PMID: 35692617 DOI: 10.1039/d0ra01936d
    A new series of lanthanum(iii) complexes was synthesized using a p-anisidine-appended 1-hydroxy-2-acetonapthanone (3) Schiff base and characterized via spectroscopic methods. The ligand was synthesized via sonication and the crystalline product was characterized using X-ray crystallography. The genotoxicity of the compound was assessed primarily by the bacterial reverse mutation (Ames) test and the in vitro mammalian chromosome aberration test; in both cases, the samarium complex 5 was found to be non-mutagenic. The anti-tumor activity of complexes 4, 5, and 6 was assayed against HeLa tumor cells and screened using the MTT assay. The IC50 value of complex 5 was found to be 34 ± 1.2 μg mL-1 and this compound exhibited superior activity towards the cells compared to 4 and 6. These results were further confirmed by Hoechst 33258 staining and AO/EI dual staining, which indicated that the cells underwent an apoptosis mechanism in a dose-dependent manner. The apoptosis was further confirmed by the formation of ladders in the DNA fragmentation assay, and the western blot analysis of complex 5 suggested that the cells underwent the caspase-3-dependent pathway with PARP cleavage. Furthermore, the docking studies of complex 5 with HSA showed that it was situated in a hydrophilic cavity held by the electrostatic attraction of four hydrogen-bonding interactions. PDB ID:1BNA binds with complex 5via strong π-π stacking interactions, which facilitate binding with the major grooves of DNA strands. The above-mentioned results illustrate that for complex 5, mitochondrion-mediated apoptosis occurs via caspase-3 activation. Complex 5 binds with DNA via intercalation because of S-phase cell cycle arrest in the HeLa cells.
  3. Fulltext Luspatercept-induced reduction in transfusion requirement in α-thalassemia
    Jackson N, Khairullah S, Bee PC
    EJHaem, 2020 Jul;1(1):297-299.
    PMID: 35847726 DOI: 10.1002/jha2.54
  4. Fulltext A Cyclodextrin-Stabilized Spermine-Tagged Drug Triplex that Targets Theophylline to the Lungs Selectively in Respiratory Emergency
    Sofian ZM, Benaouda F, Wang JT, Lu Y, Barlow DJ, Royall PG, et al.
    Adv Ther (Weinh), 2020 Dec;3(12):2000153.
    PMID: 33043128 DOI: 10.1002/adtp.202000153
    Ion-pairing a lifesaving drug such as theophylline with a targeting moiety could have a significant impact on medical emergencies such as status asthmaticus or COVID-19 induced pneumomediastinum. However, to achieve rapid drug targeting in vivo the ion-pair must be protected against breakdown before the entry into the target tissue. This study aims to investigate if inserting theophylline, when ion-paired to the polyamine transporter substrate spermine, into a cyclodextrin (CD), to form a triplex, could direct the bronchodilator to the lungs selectively after intravenous administration. NMR demonstrates that upon the formation of the triplex spermine protruded from the CD cavity and this results in energy-dependent uptake in A549 cells (1.8-fold enhancement), which persists for more than 20 min. In vivo, the triplex produces a 2.4-fold and 2.2-fold increase in theophylline in the lungs 20 min after injection in rats and mice, respectively (p
  5. Fulltext Detection and Management of Intraoperative Pneumothorax during Laparoscopic Cholecystectomy
    Heyba M, Rashad A, Al-Fadhli AA
    Case Rep Anesthesiol, 2020;2020:9273903.
    PMID: 32318295 DOI: 10.1155/2020/9273903
    Intraoperative pneumothorax is a rare but potentially lethal complication during general anesthesia. History of lung disease, barotrauma, and laparoscopic surgery increase the risk of developing intraoperative pneumothorax. The diagnosis during surgery could be difficult because the signs are often nonspecific. We report a case of a middle-aged gentleman who developed right pneumothorax during an elective laparoscopic cholecystectomy. The patient had no risk factors for adverse events during the preoperative assessment (ASA1). The patient underwent general anesthesia and was put on mechanical ventilation. The first signs of abnormality immediately after surgical port insertion were tachycardia and low oxygen saturation in addition to sings of airway obstruction. The diagnosis of pneumothorax was made clinically by chest auscultation and later confirmed by intraoperative chest radiograph. Supportive treatment was started immediately through halting the surgery and manually ventilating the patient using 100% oxygen. Definitive treatment was then done by inserting an intercostal tube. After stabilizing the patient, the surgery was completed; then, the patient was extubated and shifted to the surgical ward. Postoperative computed tomography (CT) scan was done and showed only minimal liver laceration. The patient was discharged after removing the intercostal tube and was stable at the follow-up visit. Therefore, it is important to have a high index of suspicion to early detect and treat such complication. In addition, good communication with the surgeon and use of available diagnostic tools will aid in the proper management of such cases.
  6. Fulltext Optimizing Traditional Cropping Systems Under Climate Change: A Case of Maize Landraces and Bambara Groundnut
    Chimonyo VGP, Wimalasiri EM, Kunz R, Modi AT, Mabhaudhi T
    Front Sustain Food Syst, 2020 Oct 22;4:562568.
    PMID: 39036420 DOI: 10.3389/fsufs.2020.562568
    Traditional crop species are reported to be drought-tolerant and nutrient-dense with potential to contribute to sustainable food and nutrition security within marginal production systems under climate change. We hypothesized that intercropping maize landraces (Zea mays L.) with bambara groundnut (Vigna subterranea (L.) Verdc.), together with optimum management strategies, can improve productivity and water use efficiency (WUE) under climate change. Using an ex-ante approach, we assessed climate change impacts and agronomic management options, such as plant ratios, and plant sequences, on yield and WUE of intercropped maize landrace and bambara groundnut. The Agricultural Production Systems sIMulator (APSIM) model was applied over four time periods; namely past (1961-1991), present (1995-2025), mid-century (2030-2060) and late-century (2065-2095), obtained from six GCMs. Across timescales, there were no significant differences with mean annual rainfall, but late century projections of mean annual temperature and reference crop evaporation (ET0) showed average increases of 3.5°C and 155mm, respectively. By late century and relative to the present, the projected changes in yield and WUE were -10 and -15% and 5 and 7% for intercropped bambara groundnut and maize landrace, respectively. Regardless of timescale, increasing plant population improved yield and WUE of intercropped bambara groundnut. Asynchronous planting increased yield and WUE for both maize landrace (5 and 14%) and bambara groundnut (35 and 47%, respectively). Most significant improvements were observed when either crop was planted 2-3 months apart. To reduce yield gaps in intercrop systems, low-cost management options like changing plant populations and sequential cropping can increase yield and WUE under projected climate change. To further increase sustainability, there is a need to expand the research to consider other management strategies such as use of other traditional crop species, fertilization, rainwater harvesting and soil conservation techniques.
  7. Fulltext COVID-19 pandemic, oil prices, stock market, geopolitical risk and policy uncertainty nexus in the US economy: Fresh evidence from the wavelet-based approach
    Sharif A, Aloui C, Yarovaya L
    Int Rev Financ Anal, 2020 Jul;70:101496.
    PMID: 38620230 DOI: 10.1016/j.irfa.2020.101496
    In this paper, we analyze the connectedness between the recent spread of COVID-19, oil price volatility shock, the stock market, geopolitical risk and economic policy uncertainty in the US within a time-frequency framework. The coherence wavelet method and the wavelet-based Granger causality tests applied to US recent daily data unveil the unprecedented impact of COVID-19 and oil price shocks on the geopolitical risk levels, economic policy uncertainty and stock market volatility over the low frequency bands. The effect of the COVID-19 on the geopolitical risk substantially higher than on the US economic uncertainty. The COVID-19 risk is perceived differently over the short and the long-run and may be firstly viewed as an economic crisis. Our study offers several urgent prominent implications and endorsements for policymakers and asset managers.
  8. Fulltext The river water quality before and during the Movement Control Order (MCO) in Malaysia
    Lee Goi C
    Case Stud Chem Environ Eng, 2020 Sep;2:100027.
    PMID: 38620659 DOI: 10.1016/j.cscee.2020.100027
    Data in 2016 and 2017 has shown that most of Malaysia's river water quality was in Water Quality Index Class II and Class III. The implementation of the Movement Control Order (MCO) has restricted business activities, human movements as well as anthropogenic activities. The sudden decline in human activities has directly impacted the river water quality. Several observations conducted by reporters of local newspapers, reports released by the Department of Environment (DoE) and Ministry of Environment and Water have shown positive changes in water river quality.
  9. Does cyber tech spending matter for bank stability?
    Uddin MH, Mollah S, Ali MH
    Int Rev Financ Anal, 2020 Nov;72:101587.
    PMID: 38620708 DOI: 10.1016/j.irfa.2020.101587
    CyberTech has drawn academic attention in the aftermath of the global financial crisis (GFC) as banks were forced to embrace CyberTech more aggressively to cope with market competition after the crisis. Banks can improve their operational efficiency and quality of service by relying on CyberTech, but they become more vulnerable to cybersecurity. Thus, increasing investment in CyberTech becomes a strategic necessity for banks to combat cybersecurity hazards. The study investigates how disruptive digital transformation affects bank stability. In particular, it examines whether the law of diminishing marginal returns from overspending on CyberTech affects bank stability. Based on a global sample from 43 countries, we find that an increase in CyberTech spending above the threshold level adversely affects the stability of banks. The main reason behind the adverse effect of CyberTech spending on the stability of banks is that banks take more than the proportional risk for every dollar they spend on disruptive CyberTech after they cross a threshold level of spending. While results persist across sub-samples, our results indicate two important channels of technological regimes - a diminishing returns regime and an increasing returns regime. The diminishing returns regime improves bank stability through more aggressive spending on technology, and the increasing returns regime makes banks more unstable due to excess spending on disruptive CyberTech. The study has implications for cybersecurity and sustainable CyberTech spending for banks.
  10. Fulltext A novel and stable ultraviolet and infrared intensity sensor in impedance/capacitance modes fabricated from degraded CH3NH3PbI3-xClx perovskite materials
    Qasuria TA, Fatima N, Karimov KS, Ibrahim MA
    J Mater Res Technol, 2020;9(6):12795-12803.
    PMID: 38620721 DOI: 10.1016/j.jmrt.2020.09.025
    The present situation of COVID-19 diverted our focus towards utilizing the degraded solar cells for sensor application, this will help in global energy harvesting. So, here is our successful effort to reuse already degraded solar cells as ultraviolet (UV) and infrared (IR) sensor. The spin-coated perovskite (CH3NH3PbI3-XClX) has been already tested for visible light spectrum, as an extension to that now it is utilized as UV and IR intensity sensors to cover the whole spectrum. The employed CH3NH3PbI3-XClX material was used after its efficiency loss has been reached to a saturation point in photovoltaic devices. Each deposited layer was investigated from UV to the IR absorption spectrum for deepening study through UV-vis spectroscopy. In the sandwiched architecture possessing FTO/PEDOT: PSS/Perovskite/PC61BM/CdS/Au symmetry, the perovskite film has been employed as an absorbent layer, however, other layers participation also plays a key role. The resultant device yielded very good sensing performance because of the enhanced excitons generation which is attributed to the precise selection of the interfacial materials, e.g. CdS and PC61BM as an ETM and PEDOT: PSS as HTM. The impedance and capacitance of the devices within 0.01-200 kHz under varied UV and IR illumination intensities were investigated. Measurements showed that as the intensity of the light increased i.e., UV (0-200 W/m2) and IR (0-5800 W/m2), impedance decreased while capacitance increased. The current results are attributed to the increase in the concentration of charges i.e., electron-hole pairs generation depending on the built-in capacitance and frequency of the charges.
  11. Fulltext GC-MS Evaluation, Antioxidant Content, and Cytotoxic Activity of Propolis Extract from Peninsular Malaysian Stingless Bees, Tetrigona Apicalis
    Mohamed WAS, Ismail NZ, Omar EA, Abdul Samad N, Adam SK, Mohamad S
    Evid Based Complement Alternat Med, 2020;2020:8895262.
    PMID: 33381215 DOI: 10.1155/2020/8895262
    INTRODUCTION: Propolis has been used traditionally in several countries for treating various diseases as it possessed healing properties including antioxidant and anticancer qualities. In Peninsular Malaysia, Tetrigona apicalis is one of the species of stingless bees mainly found in virgin jungle reserves which largely contribute to propolis production. Therefore, this study is designed to evaluate the phytochemical contents, antioxidant properties, and the cytotoxic effect of ethanolic crude of propolis extract against MCF7 and MCF 10A cell lines.

    METHOD: The ethanolic extract of propolis (EEP) was extracted using 80% ethanol. Identification of phytochemical contents and antioxidant properties of EEP was analysed by gas chromatography-mass spectrometry (GC-MS) and using 2, 2'-azinobis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) method, respectively. The EEP cytotoxic activity was evaluated on MCF7 and MCF 10A using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay.

    RESULTS: Phytochemical contents of EEP demonstrated 28 compounds in which caryophyllene (99%), β-amyrin (96%), α-amyrin (93%), and caryophyllene oxide (93%) were the main compounds. The percentage of ABTS+ scavenging activity of EEP showed an inhibition of 9.5% with half-inhibitory concentration (IC50) value of 1.68 mg/mL. The EEP reduced MCF7 cells viability at IC50 value of 62.24 μg/mL, 44.15 μg/mL, and 32.70 μg/mL at 24, 48, and 72 hours, respectively. The IC50 value of MCF 10A was 49.55 μg/mL, 56.05 μg/mL, and 72.10 μg/mL at 24, 48, and 72 hours, respectively. The EEP cytotoxic effect of T. apicalis was more selective towards MCF7 at 72-hour incubation with a selectivity index (SI) of 2.20.

    CONCLUSION: The EEP has been shown to have antioxidants and potential bioactive compounds and inhibited proliferation of the MCF7 cells. Further studies on the EEP role in the apoptosis pathway and its screening towards other cell lines will be evaluated.

  12. Fulltext Cost burden of male infertility investigations and treatments: A survey study
    Al-Kandari AM, Alenezi A
    Urol Ann, 2020;12(4):314-318.
    PMID: 33776325 DOI: 10.4103/UA.UA_48_20
    PURPOSE: Male infertility represents 50% of all infertility problems. The management of male infertility is expensive, causing a huge burden on the patients. In this study, we aimed to calculate the cost burden of male infertility investigations and treatments.

    METHODS: A total of 600 infertile male patients from a single center in Kuwait city were asked to fulfill an internet-based survey. The survey encompassed data about the cost of different investigations and treatments of male infertility. Patients were also asked about the preference of covering their condition either through government or by private insurance.

    RESULTS: A total of 145 patients responded to the survey. Most of the patients earned 3295 United States Dollar (USD) to 6590 USD per month. The cost of the outpatient visit ranged from 131.7 to 263.4 USD. The cost of each hormonal test was 164.5 USD while the average cost of each imaging study was 131.8-164.7 USD. Most of the patients (62.8%) received medical therapy with an expense of >988.74 USD. Varicocelectomy cost ranged from 3295 to 6590 USD while the cost of testicular sperm extraction ranged from 1644 to 3294 USD. Most patients (96.3%) did not have health insurance coverage of infertility. On average, patients spent around 18% of their annual income on infertility care, excluding major surgeries.

    CONCLUSION: Male infertility is a worrisome medical condition that causes a huge burden on the Kuwait community. Effective management necessitates insurance coverage and public health support owing to the huge financial burden on the patients and their partners. Thus, policymakers should re-evaluate their protocols of spending on male infertility care.

  13. Fulltext Aging Induces Profound Changes in sncRNA in Rat Sperm and These Changes Are Modified by Perinatal Exposure to Environmental Flame Retardant
    Suvorov A, Pilsner JR, Naumov V, Shtratnikova V, Zheludkevich A, Gerasimov E, et al.
    Int J Mol Sci, 2020 Nov 04;21(21).
    PMID: 33158036 DOI: 10.3390/ijms21218252
    Advanced paternal age at fertilization is a risk factor for multiple disorders in offspring and may be linked to age-related epigenetic changes in the father's sperm. An understanding of aging-related epigenetic changes in sperm and environmental factors that modify such changes is needed. Here, we characterize changes in sperm small non-coding RNA (sncRNA) between young pubertal and mature rats. We also analyze the modification of these changes by exposure to environmental xenobiotic 2,2',4,4'-tetrabromodiphenyl ether (BDE-47). sncRNA libraries prepared from epididymal spermatozoa were sequenced and analyzed using DESeq 2. The distribution of small RNA fractions changed with age, with fractions mapping to rRNA and lncRNA decreasing and fractions mapping to tRNA and miRNA increasing. In total, 249 miRNA, 908 piRNA and 227 tRNA-derived RNA were differentially expressed (twofold change, false discovery rate (FDR) p ≤ 0.05) between age groups in control animals. Differentially expressed miRNA and piRNA were enriched for protein-coding targets involved in development and metabolism, while piRNA were enriched for long terminal repeat (LTR) targets. BDE-47 accelerated age-dependent changes in sncRNA in younger animals, decelerated these changes in older animals and increased the variance in expression of all sncRNA. Our results indicate that the natural aging process has profound effects on sperm sncRNA profiles and this effect may be modified by environmental exposure.
    MeSH terms: Aging/physiology*; Animals; Animals, Newborn; Female; Flame Retardants/toxicity*; Male; Paternal Age; Pregnancy; Prenatal Exposure Delayed Effects/chemically induced; Prenatal Exposure Delayed Effects/genetics; Prenatal Exposure Delayed Effects/metabolism; Spermatozoa/drug effects; Spermatozoa/metabolism*; Time Factors; Rats, Wistar; Gene Expression Regulation, Developmental/drug effects; Parturition/drug effects; Parturition/genetics; Parturition/metabolism; Rats; RNA, Small Untranslated/genetics*; RNA, Small Untranslated/metabolism
  14. Fulltext Conducting Polymers for Optoelectronic Devices and Organic Solar Cells: A Review
    R Murad A, Iraqi A, Aziz SB, N Abdullah S, Brza MA
    Polymers (Basel), 2020 Nov 09;12(11).
    PMID: 33182241 DOI: 10.3390/polym12112627
    In this review paper, we present a comprehensive summary of the different organic solar cell (OSC) families. Pure and doped conjugated polymers are described. The band structure, electronic properties, and charge separation process in conjugated polymers are briefly described. Various techniques for the preparation of conjugated polymers are presented in detail. The applications of conductive polymers for organic light emitting diodes (OLEDs), organic field effect transistors (OFETs), and organic photovoltaics (OPVs) are explained thoroughly. The architecture of organic polymer solar cells including single layer, bilayer planar heterojunction, and bulk heterojunction (BHJ) are described. Moreover, designing conjugated polymers for photovoltaic applications and optimizations of highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) energy levels are discussed. Principles of bulk heterojunction polymer solar cells are addressed. Finally, strategies for band gap tuning and characteristics of solar cell are presented. In this article, several processing parameters such as the choice of solvent(s) for spin casting film, thermal and solvent annealing, solvent additive, and blend composition that affect the nano-morphology of the photoactive layer are reviewed.
  15. Fulltext Methylene Blue Dye Photocatalytic Degradation over Synthesised Fe3O4/AC/TiO2 Nano-Catalyst: Degradation and Reusability Studies
    Moosavi S, Li RYM, Lai CW, Yusof Y, Gan S, Akbarzadeh O, et al.
    Nanomaterials (Basel), 2020 Nov 27;10(12).
    PMID: 33261010 DOI: 10.3390/nano10122360
    In this study, activated carbon (AC) from coconut shell, as a widely available agricultural waste, was synthesised in a simple one-step procedure and used to produce a magnetic Fe3O4/AC/TiO2 nano-catalyst for the degradation of methylene blue (MB) dye under UV light. Scanning electron microscopy revealed that TiO2 nanoparticles, with an average particle size of 45 to 62 nm, covered the surface of the AC porous structure without a reunion of its structure, which according to the TGA results enhanced the stability of the photocatalyst at high temperatures. The photocatalytic activities of synthesised AC, commercial TiO2, Fe3O4/AC, and Fe3O4/AC/TiO2 were compared, with Fe3O4/AC/TiO2 (1:2) exhibiting the highest catalytic activity (98%). Furthermore, evaluation of the recovery and reusability of the photocatalysts after treatment revealed that seven treatment cycles were possible without a significant reduction in the removal efficiency.
  16. Fulltext Combating Parasitic Nematode Infections, Newly Discovered Antinematode Compounds from Marine Epiphytic Bacteria
    Salikin NH, Nappi J, Majzoub ME, Egan S
    Microorganisms, 2020 Dec 11;8(12).
    PMID: 33322253 DOI: 10.3390/microorganisms8121963
    Parasitic nematode infections cause debilitating diseases and impede economic productivity. Antinematode chemotherapies are fundamental to modern medicine and are also important for industries including agriculture, aquaculture and animal health. However, the lack of suitable treatments for some diseases and the rise of nematode resistance to many available therapies necessitates the discovery and development of new drugs. Here, marine epiphytic bacteria represent a promising repository of newly discovered antinematode compounds. Epiphytic bacteria are ubiquitous on marine surfaces where they are under constant pressure of grazing by bacterivorous predators (e.g., protozoans and nematodes). Studies have shown that these bacteria have developed defense strategies to prevent grazers by producing toxic bioactive compounds. Although several active metabolites against nematodes have been identified from marine bacteria, drug discovery from marine microorganisms remains underexplored. In this review, we aim to provide further insight into the need and potential for marine epiphytic bacteria to become a new source of antinematode drugs. We discuss current and emerging strategies, including culture-independent high throughput screening and the utilization of Caenorhabditis elegans as a model target organism, which will be required to advance antinematode drug discovery and development from marine microbial sources.
  17. Fulltext Cardiovascular health decline in adolescent girls in the NGHS cohort, 1987-1997
    Gooding HC, Ning H, Perak AM, Allen N, Lloyd-Jones D, Moore LL, et al.
    Prev Med Rep, 2020 Dec;20:101276.
    PMID: 33344149 DOI: 10.1016/j.pmedr.2020.101276
    Adolescence is a critical time for the preservation or loss of cardiovascular health. We aimed to describe trajectories of cardiovascular health in adolescent girls and identify early adolescent factors associated with cardiovascular health in young adulthood. We used data from the National Growth and Health Study, a longitudinal cohort of 2,379 girls followed annually from ages 9-19 years. We classified participants as having ideal, intermediate, or poor levels of the seven cardiovascular health metrics at four developmental stages: early (ages 9-11), middle (ages 12-14), and late (ages 15-17) adolescence, and early young adulthood (ages ≥ 18). We calculated total cardiovascular health scores (range 0-14) at each stage and empirically identified patterns of cardiovascular health trajectories. We examined associations between trajectory group membership and various demographic, behavioral, and physiological factors. Mean cardiovascular health scores declined with age from 10.8 to 9.4 in white girls and 10.3 to 8.9 in black girls; 17% of white girls and 23% of black girls had low cardiovascular health (score 
  18. Fulltext THz Spectroscopy as a Versatile Tool for Filler Distribution Diagnostics in Polymer Nanocomposites
    Gorokhov G, Bychanok D, Gayduchenko I, Rogov Y, Zhukova E, Zhukov S, et al.
    Polymers (Basel), 2020 Dec 18;12(12).
    PMID: 33353036 DOI: 10.3390/polym12123037
    Polymer composites containing nanocarbon fillers are under intensive investigation worldwide due to their remarkable electromagnetic properties distinguished not only by components as such, but the distribution and interaction of the fillers inside the polymer matrix. The theory herein reveals that a particular effect connected with the homogeneity of a composite manifests itself in the terahertz range. Transmission time-domain terahertz spectroscopy was applied to the investigation of nanocomposites obtained by co-extrusion of PLA polymer with additions of graphene nanoplatelets and multi-walled carbon nanotubes. The THz peak of permittivity's imaginary part predicted by the applied model was experimentally shown for GNP-containing composites both below and above the percolation threshold. The physical nature of the peak was explained by the impact on filler particles excluded from the percolation network due to the peculiarities of filler distribution. Terahertz spectroscopy as a versatile instrument of filler distribution diagnostics is discussed.
  19. Fulltext Investigating the Properties of Cetyltrimethylammonium Bromide/Hydroxylated Graphene Quantum Dots Thin Film for Potential Optical Detection of Heavy Metal Ions
    Anas NAA, Fen YW, Yusof NA, Omar NAS, Ramdzan NSM, Daniyal WMEMM
    Materials (Basel), 2020 Jun 06;13(11).
    PMID: 32517196 DOI: 10.3390/ma13112591
    The modification of graphene quantum dots (GQDs) may drastically enhance their properties, therefore resulting in various related applications. This paper reported the preparation of novel cetyltrimethylammonium bromide/hydroxylated graphene quantum dots (CTAB/HGQDs) thin film using the spin coating technique. The properties of the thin film were then investigated and studied. The functional groups existing in CTAB/HGQDs thin film were confirmed by the Fourier transform infrared (FTIR) spectroscopy, while the atomic force microscope (AFM) displayed a homogenous surface of the thin film with an increase in surface roughness upon modification. Optical characterizations using UV-Vis absorption spectroscopy revealed a high absorption with an optical band gap of 4.162 eV. Additionally, the photoluminescence (PL) spectra illustrated the maximum emission peak of CTAB/HGQDs thin film at a wavelength of 444 nm. The sensing properties of the as-prepared CTAB/HGQDs thin film were studied using a surface plasmon resonance technique towards the detection of several heavy metal ions (HMIs) (Zn2+, Ni2+, and Fe3+). This technique generated significant results and showed that CTAB/HGQDs thin film has great potential for HMIs detection.
  20. Fulltext A Sensitive Impedimetric Aptasensor Based on Carbon Nanodots Modified Electrode for Detection of 17ß-Estradiol
    Mat Zaid MH, Abdullah J, Rozi N, Mohamad Rozlan AA, Abu Hanifah S
    Nanomaterials (Basel), 2020 Jul 10;10(7).
    PMID: 32664193 DOI: 10.3390/nano10071346
    A simple and sensitive aptasensor based on conductive carbon nanodots (CDs) was fabricated for the detection of 17ß-Estradiol (E2). In the present study, the hydrothermal synthesis of carbon nanodots was successfully electrodeposited on a screen-printed electrode (SPE) as a platform for immobilization of 76-mer aptamer probe. The morphology and structure of the nanomaterial were characterized by UV-visible absorption spectra, Fluorescence spectra, Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR). Moreover, cyclic voltammetry and electrochemical impedance spectroscopy were used to investigate the electrochemical performance of the prepared electrodes. Subsequently, impedimetric (EIS) measurements were employed to investigate the relative impedances changes before and after E2 binding, which results in a linear relationship of E2 concentration in the range of 1.0 × 10-7 to 1.0 × 10 -12 M, with a detection limit of 0.5 × 10-12 M. Moreover, the developed biosensor showed high selectivity toward E2 and exhibited excellent discrimination against progesterone (PRG), estriol (E3) and bisphenol A (BPA), respectively. Moreover, the average recovery rate of spiked river water samples with E2 ranged from 98.2% to 103.8%, with relative standard deviations between 1.1% and 3.8%, revealing the potential application of the present biosensor for E2 detection in water samples.
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