Tungsten trioxide (WO₃) possesses a small band gap energy of 2.4-2.8 eV and is responsive to both ultraviolet and visible light irradiation including strong absorption of the solar spectrum and stable physicochemical properties. Thus, controlled growth of one-dimensional (1D) WO₃ nanotubular structures with desired length, diameter, and wall thickness has gained significant interest. In the present study, 1D WO₃ nanotubes were successfully synthesized via electrochemical anodization of tungsten (W) foil in an electrolyte composed of 1 M of sodium sulphate (Na₂SO₄) and ammonium fluoride (NH₄F). The influence of NH₄F content on the formation mechanism of anodic WO₃ nanotubular structure was investigated in detail. An optimization of fluoride ions played a critical role in controlling the chemical dissolution reaction in the interface of W/WO₃. Based on the results obtained, a minimum of 0.7 wt% of NH₄F content was required for completing transformation from W foil to WO₃ nanotubular structure with an average diameter of 85 nm and length of 250 nm within 15 min of anodization time. In this case, high aspect ratio of WO₃ nanotubular structure is preferred because larger active surface area will be provided for better photocatalytic and photoelectrochemical (PEC) reactions.
In this work, the oil palm empty fruit bunch (EFB) fiber was used as a source of lignocellulosic filler to fabricate a novel type of cost effective biodegradable composite, based on the aliphatic aromatic co-polyester poly(butylene adipate-co-terephtalate) PBAT (Ecoflex™), as a fully biodegradable thermoplastic polymer matrix. The aim of this research was to improve the new biocomposites' performance by chemical modification using succinic anhydride (SAH) as a coupling agent in the presence and absence of dicumyl peroxide (DCP) and benzoyl peroxide (BPO) as initiators. For the composite preparation, several blends were prepared with varying ratios of filler and matrix using the melt blending technique. The composites were prepared at various fiber contents of 10, 20, 30, 40 and 50 (wt %) and characterized. The effects of fiber loading and coupling agent loading on the thermal properties of biodegradable polymer composites were evaluated using thermal gravimetric analysis (TGA). Scanning Electron Microscopy (SEM) was used for morphological studies. The chemical structure of the new biocomposites was also analyzed using the Fourier Transform Infrared (FTIR) spectroscopy technique. The PBAT biocomposite reinforced with 40 (wt %) of EFB fiber showed the best mechanical properties compared to the other PBAT/EFB fiber biocomposites. Biocomposite treatment with 4 (wt %) succinic anhydride (SAH) and 1 (wt %) dicumyl peroxide (DCP) improved both tensile and flexural strength as well as tensile and flexural modulus. The FTIR analyses proved the mechanical test results by presenting the evidence of successful esterification using SAH/DCP in the biocomposites' spectra. The SEM micrograph of the tensile fractured surfaces showed the improvement of fiber-matrix adhesion after using SAH. The TGA results showed that chemical modification using SAH/DCP improved the thermal stability of the PBAT/EFB biocomposite.
Candida (C.) albicans infection in its biofilm mode of growth has taken centre point with the increasing recognition of its role in human infections due to the development of resistance to the commonly used antibiotic or phenotypic adaptation within the biofilm. Hence, in this study the inhibitory effect of methanol extract of Cassia (C.) spectabilis leaves was evaluated against biofilm forming C. albicans.
The adsorption of methylene blue (MB) from aqueous solution using a low-cost adsorbent, rejected tea (RT), has been studied by batch adsorption technique. The adsorption experiments were carried out under different conditions of initial concentration (50-500 mg/L), solution pH 3-12, RT dose (0.05-1g) and temperature (30-50 degrees C). The equilibrium data were fitted to Langmuir and Freundlich isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model with maximum monolayer adsorption capacities found to be 147, 154 and 156 mg/g at 30, 40 and 50 degrees C, respectively. Three kinetic models, pseudo-first-order, pseudo-second-order and intraparticle diffusion were employed to describe the adsorption mechanism. The experimental results showed that the pseudo-second-order equation is the best model that describes the adsorption behavior with the coefficient of correlation R(2)>or=0.99. The results suggested that RT has high potential to be used as effective adsorbent for MB removal.
Oil palm fronds (OPF) were used to prepare activated carbon (PFAC) using physiochemical activation method, which consisted of potassium hydroxide (KOH) treatment and carbon dioxide gasification. The effects of the preparation variables, which were activation temperature, activation time and chemical impregnation ratios (KOH: char by weight), on the carbon yield and bentazon removal were investigated. Based on the central composite design (CCD), two factor interaction (2FI) and quadratic models were, respectively, employed to correlate the PFAC preparation variables to the bentazon removal and carbon yield. From the analysis of variance (ANOVA), the most influential factor on each experimental design response was identified. The optimum conditions for preparing activated carbon from OPF were found as follows: activation temperature of 850 degrees C, activation time of 1h and KOH:char ratio of 3.75:1. The predicted and experimental results for removal of bentazon and yield of PFAC were 99.85%, 20.5 and 98.1%, 21.6%, respectively.
Rice husk is a base adsorbent for pollutant removal. It is a cost-effective material and a renewable resource. This study provides the physicochemical characterization of chemically and thermally treated rice husk adsorbents for phenol removal from aqueous solutions. We revealed new functional groups on rice husk adsorbents by Fourier transform infrared spectroscopy, and observed major changes in the pore structure (from macro-mesopores to micro-mesopores) of the developed rice husk adsorbents using scanning electron microscopy. Additionally, we studied their surface area and pore size distribution, and found a greater enhancement of the morphological structure of the thermally treated rice husk compared with that chemically treated. Thermally treated adsorbents presented a higher surface area (24-201 m2.g-1) than those chemically treated (3.2 m2.g-1). The thermal and chemical modifications of rice husk resulted in phenol removal efficiencies of 36%-64% and 28%, respectively. Thus, we recommend using thermally treated rice husk as a promising adsorbent for phenol removal from aqueous solutions.
A rapid and sensitive sandwich electrochemical immunosensor was developed based on the fabrication of the graphene/polyaniline (GP/PANI) nanocomposite onto screen-printed gold electrode (SPGE) for detection of tuberculosis biomarker 10-kDa culture filtrate protein (CFP10). The prepared GP/PANI nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The chemical bonding and morphology of GP/PANI-modified SPGE were studied by Raman spectroscopy and FESEM coupled with energy dispersive X-ray spectroscopy, respectively. From both studies, it clearly showed that GP/PANI was successfully coated onto SPGE through drop cast technique. Cyclic voltammetry was used to study the electrochemical properties of the modified electrode. The effective surface area for GP/PANI-modified SPGE was enhanced about five times compared with bare SPGE. Differential pulse voltammetry was used to detect the CFP10 antigen. The GP/PANI-modified SPGE that was fortified with sandwich type immunosensor exhibited a wide linear range (20⁻100 ng/mL) with a low detection limit of 15 ng/mL. This proposed electrochemical immunosensor is sensitive, low sample volume, rapid and disposable, which is suitable for tuberculosis detection in real samples.
Several microscopy methods have been developed to assess the morphological changes in cells in the investigations of the mode of cell death in response to a stimulus. Our recent finding on the treatment of the IC50 concentration (26.67 μg/mL) of Polyalthia longifolia leaf extract indicated the induction of apoptotic cell death via the regulation of miRNA in HeLa cells. Hence, the current study was conducted to validate the function of these downregulated microRNAs in P. longifolia-treated HeLa cells using microscopic approaches. These include scanning electron microscope (SEM), transmission electron microscope (TEM), and acridine orange/propidium iodide (AO/PI)-based fluorescent microscopy techniques by observing the morphological alterations to cells after transfection with mimic miRNA. Interestingly, the morphological changes observed in this study demonstrated the apoptotic hallmarks, for instance, cell blebbing, cell shrinkage, cytoplasmic and nuclear condensation, vacuolization, cytoplasmic extrusion, and the formation of apoptotic bodies, which proved the role of dysregulated miRNAs in apoptotic HeLa cell death after treatment with the P. longifolia leaf extract. Conclusively, the current study proved the crucial role of downregulated miR-484 and miR-221-5p in the induction of apoptotic cell death in P. longifolia-treated HeLa cells using three approaches-SEM, TEM, and AO/PI-based fluorescent microscope.
Alginate-based bipolymeric-nanobioceramic composite matrices for sustained drug release were developed through incorporation of nano-hydroxyapatite [nHAp] powders within ionotropically-gelled calcium ion-induced alginate-poly (vinyl pyrrolidone) blends polymeric systems. nHAp powders were synthesized by precipitation technique using calcium hydroxide [Ca(OH)2] and orthophosphoric acid [H3PO4] as raw materials. The average particle size of these was synthesized. nHAp powders was found as 19.04 nm and used to prepare nHAp-alginate-PVP beads containing DS. These beads exhibited drug entrapment efficiency (%) of 65.82±1.88 to 94.45±3.72% and average bead sizes of 0.98±0.07 to 1.23±0.15 mm. These beads were characterized by scanning electron microscopy (SEM) and Fourier transform-infra red (FTIR) spectroscopy analyses. Various nHAp-alginate-PVP beads containing DS exhibited prolonged sustained drug release and followed the Koresmeyer-Peppas model of drug release (R2=0.9908-0.9978) with non-Fickian release (anomalous transport) mechanism (n=0.73-0.84) for drug release over 8 h.
Microencapsulation is a process by which tiny parcels of an active ingredient are packaged within a second material for the purpose of shielding the active ingredient from the surrounding environment. This study aims to determine the ability of the microencapsulation technique to improve the viability of Trichoderma harzianum UPM40 originally isolated from healthy groundnut roots as effective biological control agents (BCAs). Alginate was used as the carrier for controlled release, and montmorillonite clay (MMT) served as the filler. The encapsulated Ca-alginate-MMT beads were characterised using Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). The FTIR results showed the interaction between the functional groups of alginate and MMT in the Ca-alginate-MMT beads. Peaks at 1595, 1420 and 1020 cm(-1) characterised alginate, and peaks at 1028 and 453 cm(-1) characterised MMT; both sets of peaks appeared in the Ca-alginate-MMT FTIR spectrum. The TGA analysis showed an improvement in the thermal stability of the Ca-alginate-MMT beads compared with the alginate beads alone. SEM analysis revealed a homogeneous distribution of the MMT particles throughout the alginate matrix. T. harzianum UPM40 was successfully encapsulated in the Ca-alginate-MMT beads. Storage analysis of the encapsulated T. harzianum UPM40 showed that the low storage temperature of 5°C resulted in significantly (p
The presence of heavy metals in the environment results in a number of environmental problems. In this study, the potential of Rambai stem (Baccaurea motleyana) of Malaysia in removing nickel ion from aqueous solution has been evaluated. The raw material used in this study was obtained from local orchard. The collected material passed through physical preparation and treatment process. The adsorbent was thoroughly characterized by SEM, EDX and FTIR studies. The effect of initial nickel concentration, dosage of adsorbent and pH on the adsorption process were investigated. The highest adsorption capacity obtained at weak acidic conditions (pH 4-5) when dosage and initial concentrations are 0.1 and 30 ppm respectively. The percentage of removal of nickel from the solution was found to be 51%. The experimental data fitted well in Freundlich isotherms indicating the adsorption of nickel on Rambai stem (Baccaurea motleyana) followed heterogenous surface phenomena.
Litsea elliptica Blume leaves have been traditionally used as medicinal herbs because of its antimutagenicity, chemopreventative and insecticidal properties. In this study, the toxic effects of L. elliptica essential oil against Sprague-Dawley rat's red blood cells (RBCs) were evaluated. L. elliptica essential oil was given by oral gavage 5 times per week for 3 treated groups in the doses of 125, 250, and 500 mg/(kg body weight), respectively, and the control group received distilled water. Full blood count, RBC osmotic fragility, RBC morphological changes, and RBC membrane lipid were analyzed 28 d after the treatment. Although L. elliptica essential oil administration had significantly different effects on hemoglobin (Hb), mean cell hemoglobin concentration (MCHC), mean cell volume (MCV), and mean cell hemoglobin (MCH) in the experimental groups as compared to the control group (P<0.05), the values were still within the normal range. L. elliptica induced morphological changes of RBC into the form of echinocyte. The percentage of echinocyte increased significantly among the treated groups in a dose-response manner (P<0.001). The concentrations of RBC membrane phospholipids and cholesterol of all treated groups were significantly lower than those of control group (P<0.001). However, the RBC membrane osmotic fragility and total proteins of RBC membrane findings did not differ significantly between control and treated groups (P>0.05). It is concluded that structural changes in the RBC membrane due to L. elliptica essential oil administration did not cause severe membrane damage.
Textile wastewater, one of the most polluted industrial effluents, generally contains substantial amount of dyes and chemicals that will cause increase in the COD, colour and toxicity of receiving water bodies if not properly treated. Current treatment methods include chemical and biological processes; the efficiency of the biological treatment method however, remains uncertain since the discharged effluent is still highly coloured. In this study, granules consisting mixed culture of decolourising bacteria were developed and the physical and morphological characteristics were determined. After the sixth week of development, the granules were 3-10 mm in diameter, having good settling property with settling velocity of 70 m/h, sludge volume index (SVI) of 90 to 130 mL/g, integrity coefficient of 3.7, and density of 66 g/l. Their abilities to treat sterilised raw textile wastewater were evaluated based on the removal efficiencies of COD (initial ranging from 200 to 3,000 mg/L), colour (initial ranging from 450 to 2000 ADMI) of sterilised raw textile wastewater with pH from 6.8 to 9.4. Using a sequential anaerobic-aerobic treatment cycle with hydraulic retention time (HRT) of 24 h, maximum removal of colour and COD achieved was 90% and 80%, respectively.
Polyhydroxyalkanoates (PHA) are naturally occurring biopolyesters that have great potential in the medical field. However, the leachables resulting from sterilization process of the biomaterials may exert toxic effect including genetic damage. Here, we demonstrate that although gamma-irradiation of poly(3-hydroxybutyrate-co-50 mol % 4-hydroxybutyrate) [P(3HB-co-4HB)] did not cause any change in the morphology by scanning electron microscopy, there was a significant degradation of this copolymer where the molecular weight was reduced by 37% after sterilization indicating the generation of leachables. Therefore, further investigation on the ability of the extract of this poststerilized copolymer to induce mutagenic effect was performed using Ames test (S. typhimurium strains TA1535 and TA1537) and umu test (S. typhimurium strain TA1535/pSK1002). Additionally, the capability of the extract to induce clastogenic effect was determined using Chinese hamster lung V79 fibroblast cells. Our results showed that with and without the presence of S9 metabolic activation, no mutagenic effects were observed in both Ames and umu tests when treated with P(3HB-co-4HB) extract. Similarly, treatment of P(3HB-co-4HB) extract in V79 fibroblast cells showed no significant production of micronuclei when compared with the positive control (Mitomycin C). Together, these results indicate that leachables of poststerilized P(3HB-co-4HB) cause no mutagenic and clastogenic effects.
Microgravity, hypergravity, vibration, ionizing radiation and temperature fluctuations are major factors of outer space flight affecting human organs and tissues. There are several reports on the effect of space flight on different human cell types of mesenchymal origin while information regarding changes to vascular endothelial cells is scarce. Ultrastructural and cytophysiological features of macrovascular endothelial cells in outer space flight and their persistence during subsequent culturing were demonstrated in the present investigation. At the end of the space flight, endothelial cells displayed profound changes indicating cytoskeletal lesions and increased cell membrane permeability. Readapted cells of subsequent passages exhibited persisting cytoskeletal changes, decreased metabolism and cell growth indicating cellular senescence.
In this paper, we report how few layers graphene that can be produced in large quantity with low defect ratio from exfoliation of graphite by using a high intensity probe sonication in water containing liquid hand soap and PVP. It was founded that the graphene powder obtained by this simple exfoliation method after the heat treatment had an excellent exfoliation into a single or layered graphene sheets. The UV-visible spectroscopy, FESEM, TEM, X-ray powder diffraction and Raman spectroscopy was used to analyse the graphene product. The thermal diffusivity of the samples was analysed using a highly accurate thermal-wave cavity photothermal technique. The data obtained showed excellent enhancement in the thermal diffusivity of the graphene dispersion. This well-dispersed graphene was then used to fabricate an electrically conductive polymer-graphene film composite. The results demonstrated that this low cost and environmental friendly technique allowed to the production of high quality layered graphene sheets, improved the thermal and electrical properties. This may find use in the wide range of applications based on graphene.
Anionic surfactants are one of the pollutants derived from particulate matter (PM) and adversely affect the health of living organisms. In this study, the compositions of surfactants extracted from PM and vehicle soot collected in an urban area were investigated. A high-volume air sampler was used to collect PM sample at urban area based on coarse (> 1.5 µm) and fine (electron microscope. Results revealed that the MBAS concentration was dominated by fine mode particles (6.03 ± 3.97 µmol g-1), whereas heavy-duty vehicles, such as buses, demonstrated the highest surfactant concentration with an average value of 0.340 ± 0.180 µmol g-1. The structure of collected PM for all samples mostly appeared to be an irregular shape with the size range of ultrafine particles (0.05-0.2 µm). The emission of surfactants from diesel and petrol vehicles, especially at urban areas, should be a major concern, because they could negatively affect human health and the environment.
Active ingredients of ginsenoside, Rg1 and Re, are able to inhibit the proliferation of vascular smooth muscle cells and promote the growth of vascular endothelial cells. These capabilities are of interest for developing a novel drug-eluting stent to potentially solve the current problem of late-stent thrombosis and poor endotheliazation. Therefore, this study was aimed to incorporate ginsenoside into degradable coating of poly(lactic-co-glycolic acid) (PLGA). Drug mixture composed of ginseng extract and 10% to 50% of PLGA (xPLGA/g) was coated on electropolished stainless steel 316L substrate by using a dip coating technique. The coating was characterized principally by using attenuated total reflectance-Fourier transform infrared spectroscopy, scanning electron microscopy and contact angle analysis, while the drug release profile of ginsenosides Rg1 and Re was determined by using mass spectrometry at a one month immersion period. Full and homogenous coating coverage with acceptable wettability was found on the 30PLGA/g specimen. All specimens underwent initial burst release dependent on their composition. The 30PLGA/g and 50PLGA/g specimens demonstrated a controlled drug release profile having a combination of diffusion- and swelling-controlled mechanisms of PLGA. The study suggests that the 30PLGA/g coated specimen expresses an optimum composition which is seen as practicable for developing a controlled release drug-eluting stent.
Poor solubility and bioavailability of drugs are often affected by its microscopic structural properties. Nitrofurantoin (NF), a Biopharmaceutics Classification System class II item, has a low water solubility with low plasma concentrations. To improve its therapeutic efficacy, formulation strategy of solid dispersion (SD) and co-crystallization are compared herein. The co-crystal is prepared with citric acid in 1:1 stoichiometric ratio while SD consists of 30% w/w nitrofurantoin and 70% w/w hydroxypropyl methylcellulose (HPMC) as the carrier system. As a control, the physical mixture of NF and HPMC was prepared. All the preparations were characterized with differential scanning calorimetry (DSC), attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), microscopy analysis, solubility, and dissolution studies. The formation of co-crystal, solvent evaporated, and spray-dried SD are confirmed by the ATR-FTIR where peaks shifting of several functional groups indicate the formation of the hydrogen bond. Dissolution studies showed a greater initial dissolution rate in co-crystal than SD despite the possible presence of amorphous content in the SD system. Overall, co-crystal is concluded to be a better approach than SD for an effective dissolution.
This paper investigated the effects of critical-point drying (CPD) and hexamethyldisilazane (HMDS) sample preparation techniques for cervical cells on field emission scanning electron microscopy and energy dispersive X-ray (FE-SEM/EDX). We investigated the visualization of cervical cell image and elemental distribution on the cervical cell for two techniques of sample preparation. Using FE-SEM/EDX, the cervical cell images are captured and the cell element compositions are extracted for both sample preparation techniques. Cervical cell image quality, elemental composition, and processing time are considered for comparison of performances. Qualitatively, FE-SEM image based on HMDS preparation technique has better image quality than CPD technique in terms of degree of spread cell on the specimen and morphologic signs of cell deteriorations (i.e., existence of plate and pellet drying artifacts and membrane blebs). Quantitatively, with mapping and line scanning EDX analysis, carbon and oxygen element compositions in HMDS technique were higher than the CPD technique in terms of weight percentages. The HMDS technique has shorter processing time than the CPD technique. The results indicate that FE-SEM imaging, elemental composition, and processing time for sample preparation with the HMDS technique were better than CPD technique for cervical cell preparation technique for developing computer-aided screening system.