The fabrication and characterization of transparent conductors based on single walled carbon nanotube (SWCNT) thin films were carried out in controlled environment and its performance compared. Here, we demonstrate the fabrication of thin, transparent, optically homogeneous, electrically conducting films of metallic enriched single-walled carbon nanotubes via three different deposition techniques namely dip coating, vacuum filtration and Langmuir Blodgett. Optical characterization showed that the maximum transmittance, TM, in Vis region is ~ 96.3% and minimum surface roughness, Ra ~ 4.87 nm achieved via Langmuir-Blodgett technique. I-V characteristics shows minimum sheet resistance, Rs ~ 3.62 × 103 Ω/sq and maximum conductivity, σ ~ 27.65 Ω-1cm-1 for vacuum filtration technique. It is shown that SWCNT deposition technique significantly affects the optical and electrical characteristics of resulting thin films. Langmuir Blodgett method produced film with the lowest surface roughness of Ra ~ 4.87 nm and uniform conductivity of σ ~ 0.025 Ω-1cm-1, whereas vacuum filtration method produced film with the highest surface roughness of Ra ~ 12.83 nm and non-uniform conductivity, σ, ranging from ~ 0.199 to ~0.017 Ω-1cm-1 depending on the film dimensions.
Polymer-based nanocomposites have attracted a lot of attention for amperometric biosensor development due to their general physical and chemical properties including biocompatibility, film-forming ability, stability and different functional groups that can be bonded with other biomolecues. In this study, poly-4-vinlyridine homopolymer (P4VP) and polylactic acid-block-poly(2-vinylpyridine) block copolymer (PLA-b-P2VP) were used to hybridize with gold precursors (Au3+) based on the association between the nitrogen of the pyridine group of P4VP or P2VP block with gold precursors. P4VP/Au3+ and PLA-b-P2VP/Au3+ nanocomposites were prepared with ratio of gold to P2VP or P4VP (10:1). The Au3+ in both polymers was reduced to gold nanoparticles (AuNPs) via in-situ approach by using hydrazine. Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-vis), transmission electron microscopy (TEM) and cyclic voltammetry (CV) were used to characterize the structural, morphological and electrochemical properties of the nanocomposites. The peak currents of P4VP/AuNPs and PLA-b-P2VP/AuNPs nanocomposites modified electrode were 6.685 nA and 69.432 nA, respectively, which are much lower than bare electrode (205.019 nA) due to the non-conductivity of P4VP and PLA-b-P2VP. In order to improve the electron transfer capability of electrode, graphene oxide (GO) was blended and electrochemically reduced to obtain P4VP/AuNPs/rGO and PLA-b-P2VP/AuNPs/rGO nanocomposites. After immobilization of these two nanocomposites on electrode through drop casting method, the peak currents of P4VP/AuNPs/rGO and PLA-b-P2VP/AuNPs/rGO nanocomposites modified electrode were 871.172 nA and 663.947 nA, respectively, which are much higher than bare electrode (205.019 nA) and shown good capability to accelerate electron transfer. Based on these characterizations, P4VP/AuNPs/rGO has potential as the nanocomposite to modify the electrode for enzymatic biosensor development.
A planar Graphene Field-Effect Transistor GFET performance with 60 nm gate length was evaluated in discovering new material to meet the relentless demand for higher performance-power saving features. The ATHENA and ATLAS modules of SILVACO TCAD simulation tool was employed to virtually design and assess the electrical performance of GFET. The developed model was benchmarked with the established results obtained from the DESSIS simulator model by using the same graphene channel’s parameters and simulated at fixed threshold voltage of 0.4V. The GFET was also analyzed and ranked its performance for four different gate oxides which includes HfO2, Al2O3, TiO2, and Ta2O5. Compared to the benchmarked device, our GFET shows a competitive performance although it possesses a lower drive current (ION). However, the leakage current (IOFF), subthreshold swing (SS) and the device’s switching capability (ION/IOFF) are more superior than those of the benchmarked device, with an improvement of 99%, 48.3% and 99.36%, respectively. The with different gate dielectrics were also proven to possess a lower IOFF, competitive ION, smaller SS and better switching capability compared to the established DESSISS model. The graphene parameters in this experiment can be utilized for further optimization of GFET with smaller gate lengths.
A one-pot green sonochemical process assisted by ascorbic acid as the reducing agent to produce highly reduced graphene oxide (rGO) decorated with silver nanoparticles (AgNPs) is demonstrated. A complete removal of oxygen-containing group in the GO sheets was confirmed by no observation of the peak corresponds to C-O, C=O and -OH bond. The unexpected decrease of peak intensity corresponds to sp2 hybridized C=C group is explained by a so-called bond polarity effect. The peak observed at ~400 nm seems to show the presence of AgNPs and the red shifting of C=C peak to ~270 nm after the introduction of ascorbic acid indicates the formation of highly reduced GO. The increase of AgNPs size and the crumpled silk-like morphology after the introduction of ascorbic acid also indicate the aggressive reduction of both AgNPs and GO. The increase of ID/IG ratio after the introduction of ascorbic acid seems to indicate the increase of the number of small sp2 domains, the presence of unrepaired defects and the restoration of the sp2 network. This work provides the promising green sonochemical approach by utilizing non-toxic and environmental-friendly reducing agent to produce highly reduced GO decorated with AgNPs for various applications.
In this article, the effect of heating duration on the synthesis of silicon carbide nanotubes (SiCNTs) was reported. SiCNTs were synthesized from blend of silicon dioxide (SiO2) and multi-walled carbon nanotubes (MWCNTs) in the ratio of 1:3 by using the microwave heating at 1400°C and maintained at duration of 20, 40 and 60 min, respectively. SiCNTs synthesized at heating duration of 40 and 60 min showed the presence of single phase β-SiC in X-ray diffraction patterns. Meanwhile, field emission scanning electron microscope images showed that SiCNTs were formed and no residual of SiO2 and MWCNTs was observed for SiCNTs formed at heating duration of 40 and 60 min. Transmission electron microscopy images showed the SiCNTs have inter-planar spacing of 0.263 nm and tubular structure of nanotube were retained. The peak corresponded to β-SiC was observed at wavelength of 465 nm from the photoluminescence spectroscopy and associated with energy band gap of 2.67 eV. Absorption bands of Si-C bond were detected at 806.23 cm-1 from the fourier transform infrared spectra. High purity SiCNTs was obtained at 40 and 60 min as indicated by low weight loss by thermo-gravimetric analysis. 40 min is the most suitable heating duration for the synthesis of single phase β-SiCNTs.
Superkapasitor MEMS khususnya dengan reka bentuk elektrod antara digit (IDE), telah menarik minat pada masa kini dalam bidang seperti bioMEMS, bioperubatan implan, peranti kuasa elektronik dan aplikasi berkuasa tinggi disebabkan kapasiti pengecasannya yang tinggi. Kajian ini membentangkan superkapasitor MEMS dengan lapisan nano grafin tumbuh di atas elektrod. Superkapasitor MEMS terdiri daripada silikon dioksida (SiO2), nikel, grafin, polipirol (Ppy) dan lapisan alkohol polivinil (PVA). Tumpuan diberikan kepada fabrikasi struktur lapisan nano grafin atas elektrod superkapasitor MEMS melalui beberapa proses seperti pemendapan wap kimia secara peningkatan plasma (PECVD), penyejatan alur e dan salutan pusing. Grafin tumbuh melalui proses PECVD selama 10 minit pada kuasa 40 Watt dan pada suhu antara 400°C dan 1000°C. Spektrum Raman menunjukkan puncak pada 1340 dan 1580 cm-1 mewakili jalur D dan G. Puncak 2D wujud dalam julat 2600 - 3000 cm-1. Nisbah bagi keamatan puncak 2D terhadap puncak G pada 1000°C adalah 0.43 menunjukkan kualiti yang baik bagi banyak lapisan grafin
Kertas ini mengkaji teknologi pengelupasan untuk menghasilkan grafin, grafin oksida (GO) dan grafin oksida terturun
(rGO). Empat teknologi pengelupasan yang utama dikenal pasti dalam tinjauan ini iaitu pengelupasan mekanik,
pengelupasan cecair, interkalasi-pengelupasan dan pengoksidaan-pengelupasan-penurunan. Setiap teknologi ini
dibincangkan daripada segi kualiti grafin, grafit nanoplat, GO dan rGO yang dihasilkan dan langkah utama proses
termasuk bahan kimia yang digunakan. Kami juga membuat satu kajian kemudah-capaian dan analisis sensitiviti untuk
menubuhkan satu kilang penghasilan grafin yang berasaskan teknologi pengelupasan, saiz pasaran grafin dan bahan
mentahnya iaitu grafit. Berdasarkan kitar gemburan Gartner, teknologi dan produk yang berasaskan grafin terletak di
tiga lokasi iaitu lembah kekecewaan, cerun pencerahan dan dataran tinggi produktivit
MeSH terms: Animals; Autonomic Nervous System Diseases; Diabetic Neuropathies; Gastropoda
Sel suria adalah peranti semikonduktor yang menukar tenaga matahari kepada tenaga elektrik. Sel suria generasi
pertama terdiri dari sel suria silikon (Si). Pada masa ini, hampir 90% daripada pasaran pengeluaran fotovolta (PV)
adalah berdasarkan wafer Si. Ini disebabkan oleh kecekapan dan ketahanan yang tinggi serta jangka hayat yang
lama iaitu selama 30 tahun. Proses pemfabrikasian piawai bagi sel suria Si dimulakan dengan proses pencucian dan
penteksturan wafer Si, difusi Fosforus untuk pembentukan pemancar, pembentukan elektrod atas dan bawah melalui
proses cetakan skrin dan proses pembakaran yang melengkapkan fabrikasi sel suria. Dalam industri, proses piawai
ini dilakukan pada wafer Si jenis-p. Wafer jenis-n pula mempunyai potensi yang tinggi untuk menghasilkan sel suria Si
yang berkecekapan tinggi. Namun, proses untuk menghasilkan sel suria silikon atas Si wafer jenis-n melalui proses yang
lebih rumit dan lama seperti dua peringkat proses difusi menjadikan wafer jenis-p digunakan secara meluas kerana
dapat merendahkan kos pemfabrikasian. Dalam penyelidikan ini, analisis bagi arus-voltan bagi sel suria Si jenis-n yang
difabrikasi menggunakan adaptasi proses fabrikasi piawai bagi wafer Si jenis-p akan dibincangkan. Daripada kajian
simulasi menggunakan perisian PC1D, didapati bahawa kecekapan bagi sel suria jenis-p dan jenis-n yang difabrikasi
dengan kaedah yang sama adalah 19.63% dan 20.16%. Manakala keputusan eksperimen menunjukkan kecekapan
sebanyak 9.44% dan 5.51% bagi sel suria jenis-p dan jenis-n.
Nanoparticles of undoped and copper doped with Fe3
O4 of three concentrations (0.5, 1.0 and 1.5) are synthesized by
sonochemical method. Structural, optical and morphological properties of these compounds were studied. Fe2+/Fe3+
ratio is found to be 2.36. Crystalline structure, lattice parameters, surface morphologies, direct and indirect band gap
energies of the synthesized compounds were estimated and the results are discussed in detail. The XDR analysis indicates
the Cu doped Fe3
O4
nanoparticles have higher crystallinity than undoped samples. Average crystallite size is found
to increase as Cu concentration increased. The FTIR results are proven by the presence of mixed magnetite-hematite
nanostructures and it is complement to the XRD results. The presence of spherical, polygonal and agglomeration forms
of the particles are visually seen in the SEM images. Direct and indirect band gap energy is found to be decreased as the
copper concentration was increased.
The present work was carried out to investigate the blood flow behavior and the severity of blockage caused in the
arterial passage due to the different geometries such as elliptical, trapezium and triangular shapes of stenosis. The study
was conducted with respect to various sizes of stenosis in terms of 70%, 80% and 90% area blockage of the arterial
blood flow. The study was carried out numerically with the help of advance computational fluid dynamic software. It
was found that the shape of the stenosis plays an important role in overall pressure drop across the blockage region
of artery. The highest level of pressure drop was observed for trapezoidal shape of stenosis followed by elliptical and
then by triangular shaped stenosis. The wall shear stress across the stenosis is great for trapezoidal shape followed by
triangular and elliptical stenosis for same blockage area in the artery.
Ammonium-enriched skim latex serum - used for absorption of contaminating ammonia gas - when composted with other rubber tree wastes, is promising as a good compost. The objective of this research was to utilize ammonium-enriched skim latex serum (S) as a raw composting ingredient after being combined with para sawdust (W1) and para rubber leaves (W2). Several ratios of S, W1 and W2 were experimented in a 15L composting vessel to determine the most effective compost. The best ratio was found to be 3:1:3 by weight at 12-day retention. The modified 30 L composting reactor employed with the derived optimum mixing conditions yielded N, P and K of 2.40, 1.51 and 14.84 %w/w. The growth of Brassica alboglabra after application of this compost combined with a chemical fertilizer generated the highest fresh weight (4.48 g/plant). Thus, compost from these wastes could be used as a fertilizer and logically should contribute to cost saving of waste disposal.
The environmental risk of Chromium (Cr) pollution is pronounced in soils adjacent to chromate industry. It is important to investigate the functioning of soil microorganisms in ecosystems exposed to long-term contamination by Cr. The aim of this study was to determine the effects of Cr on carbon mineralization in soil. The study was carried out in soils contaminated and uncontaminated with Cr near and away from a Cr mine in three different districts (Bozluk, Kızılyüksek and Yanıkçam) of East Mediterranean Region, Turkey. Carbon mineralization were determined in soils humidified 80% of field capacity at 28°C over 30 days under the same laboratory conditions. These results showed that carbon mineralization was greatly inhibited by the presence of Cr in all contaminated sites. Based on these results, microbial activity can use as an indicator for the Cr pollution level in the soil ecosystems.
Kaedah tindak balas permukaan (RSM) telah digunakan untuk mengoptimumkan penyediaan biokomposit rHDPE berpenguat sekam padi sebagai pengisi. Sekam padi adalah sisa pertanian yang mempunyai ciri-ciri kayu dan digunakan secara pesat dalam bidang komposit kayu plastik. Kesan parameter suhu, tekanan serta masa proses tekanan panas ke atas kekuatan tegangan telah dikaji. Reka bentuk Box Bechken telah digunakan untuk menentukan parameter optimum biokomposit yang mempunyai kekuatan tegangan yang tinggi. Model tertib kedua telah dibangunkan untuk meramalkan kekuatan tegangan berdasarkan reka bentuk komposit. Didapati bahawa komposit sesuai digunakan apabila model regresi kuadratik dengan pekali penentu bilang (R2) yang tinggi. Keadaan proses menekan yang optimum dicapai pada suhu 180°C, tekanan 1000 psi dan masa 9 min dengan pekali penentu berbilang mencapai 97%. Di bawah keadaan yang optimum ini, komposit yang mengandungi 10, 20, 30, 40 dan 50% gentian RH telah disediakan. Kekuatan tegangan dan modulus tegangan biokomposit menunjukkan peningkatan apabila kandungan gentian RH ditambah.
Presently, climate change plays an important role as it gives a serious impact to the living things on earth. Analyzing the trend of climate change is very important in identifying the pattern of changes because it can give an initial overview for future analysis. In this study, trend analysis was carried out to study the pattern of changes for five climate change parameters, such as total amount of monthly precipitation (mm), monthly average temperature (°C), monthly average global radiation (MJm–2), monthly average wind speed (m/s) and monthly average humidity (%) during the period of 1974 to 2010. Comparisons were made between two research stations, which were the Senai International Airport and Kluang Meteorological Stations. In this study, the Mann-Kendall trend test and Sen’s slope estimator test were used to identify the monotonic trend for these climate change parameters. As a result of this analysis, the precipitations showed no trend for both locations and the radiation showed no trend in Kluang from both analyses. Meanwhile, other parameters in Senai and Kluang showed a monotonic trend, according to the Tau value (Z) and the Sen’s slope value. The temperature shows a positive trend for both locations.
Twenty lines of Pisum sativum particularly developed for high yield and resistant to powdery mildew were evaluated along with two parents (Falloner and 11760-3ER) and two checks (Climex and a local cultivar) with the objectives to determine morphological characterization, yield potential and resistance to powdery mildew. On the basis of one way cluster, the 24 lines were mainly grouped into four clusters, especially on the vegetative and yield contributing traits. It was observed that the tall and high yielding lines were grouped in cluster-III while the dwarf and high yielding lines were grouped in cluster-IV. Analysis of variance (ANOVA) showed significant difference (p<0.05) in the yield of 24 pea lines. The average grain yield of the 24 pea lines ranged from 22.87 to 102.54 g. The highest grain yield was produced by PL-4 (102.54 g plant-1) followed by PL-5 (82.14 g plant-1). Of the 24 pea lines, two lines (PL-4 and PL-5) were highly resistant to powdery mildew disease. Therefore, the newly developed PL-4 and PL-5 lines were high yielding and highly resistant. Among the 19 morphological traits, six (Eigenvalue >1.0) contributed more than 80% variability among the materials.
MeSH terms: Analysis of Variance; Ascomycota; Edible Grain; Phenotype; Peas
Pueraria mirifica (PM) is a phytoestrogen-rich plant that was tested to establish if its phytosteroids could prevent estrogen dependent sarcopenia. The effect of PM on the estrogen levels, estrous cycle, toxicity, muscle mass, strength and endurance of extensor digitorum longus (EDL) and gastrocnemius muscles of ovariectomized rats was investigated. Adult female Wistar rats were divided into six groups: Sham-operated (SHAM); ovariectomized (OVX) fed with distilled water (PM0); OVX injected with 40 μg/kg estradiol benzoate (E40); (4-6) OVX fed with ethanolic extract of PM at doses of 50 (PM50), 500 (PM500) and 1000 (PM1000) mg/kg for 90 days. After treatment with all three doses of PM, no toxicity was detected to the hematopoietic system and liver function whereas the E40 group did show toxic effects. Treatment with 50 and 500 mg/kg of PM showed no effect on uterine hypertrophy and caused no arrest of the estrous cycle whereas treatment with estrogen and 1000 mg/kg of PM treatment did. The estrogen level, the cross sectional area of the EDL and the gastrocnemius muscle fiber strength and endurance were all significantly reduced in the PM0 group compared to that of the SHAM group (p<0.05) but were significantly increased in the E40, PM50, PM500 and PM1000 compared to that of the PM0 group (p<0.05). This indicated that the estrogenic activity of PM alleviated muscle atrophy and built up muscle strength and endurance. Thus, the 50 and 500 mg/kg of PM were suitable for treating estrogen dependent sarcopenia in ovariectomized rats.
Rheumatoid arthritis (RA) is a chronic disease characterized by inflammation of the joints and their lining or synovium. Previous studies showed that the synovium in RA patients is more hypoxic than normal synovium. Activated protein C (APC) has anticoagulant and anti-inflammatory effects and is highly expressed in the joints of RA patients. We examined the effect of APC on RA and normal synovial fibroblasts under hypoxic conditions. Human synovial fibroblasts were isolated from the synovial tissues of RA patients and normal controls and cells were exposed to recombinant APC under normoxic (21% oxygen) or hypoxic (1% oxygen) conditions. Cell proliferation was measured using MTT assays. Cell lysates and conditioned media were collected and assayed for matrix metalloproteinase (MMP)-2, MMP-9 and p38 using zymography and western blots. Proliferation of both normal and RA synovial fibroblasts dose-dependently increased after APC treatment in normoxic conditions. Under hypoxia, APC enhanced RA cell proliferation but had no effect on normal fibroblasts. MMP-2 production and activation were significantly augmented by APC in both cell types under normoxia and hypoxia conditions. However, activated MMP-2 was more reduced in cells under hypoxia than normoxia. APC substantially reduced the phosphorylation of p38 in normal and RA synovial fibroblasts under hypoxia. No difference in p38 phosphorylation was observed under normoxia. The receptor for APC, endothelial protein C receptor (EPCR), was elevated in normal fibroblasts under hypoxic conditions whereas in RA cells, EPCR was highly expressed under both normoxic and hypoxic conditions. We found that hypoxia enhanced the effect of APC on RA synovial fibroblasts through activation of MMP2 and inhibition of p38 phosphorylation. Our results suggested that APC may suppress joint destruction and progression of inflammation in a hypoxic RA environment.
Visual function is mainly located within the bilateral hemisphere of the occipital lobes of the brain. However, our functional magnetoencephalography (MEG) result has demonstrated the reorganization of brain activity in the occipital area in patients with left-sided brain tumour. The results showed that brain laterality changes from bilateral to unilateral activation of the occipital area. Right occipital area (contralateral areas to the tumour), shows increase intensity of activation. Diffusion tensor imaging (DTI) with fibre tracking was performed to further investigate this brain laterality modification and the findings confirmed there is an alteration in the left hemisphere fibre optic tracts. This functional modification and changes of the brain laterality and optic tracts in the brain is suspected to be the result of tumour growth induced changes. The present observation will be discussed in term of the mechanism of tumour induced reorganization and changes with the corroborating evidence from MEG, DTI and neuropsychological assessment.
How the composition of the arbuscular mycorrhizal (AM) fungal community affects plant traits of different plant species in karst environments is poorly understood. Broussonetia papyrifera (a woody shrub) and Bidens pilosa (a herbaceous plant) growing in pots in limestone soil were inoculated with an AM fungus, either Funneliformis mosseae (FM), Diversispora versiformis (DV) or Glomus diaphanum (GD) or with an inoculum mixture of all three AM fungi (bn). B. papyrifera and B. pilosa seedlings inoculated with AM fungi showed a significant increase in biomass and nitrogen and phosphorus acquisition compared with the controls, which lacked mycorrhiza. Mixed fungal inoculations significantly enhanced biomass and nitrogen and phosphorus acquisition by B. papyrifera seedlings compared with single fungal inoculations. Nitrogen and phosphorus acquisition by B. papyrifera mycorrhizal seedlings was significantly greater than that of B. pilosa mycorrhizal seedlings. Fungal composition significantly influenced the mycorrhizal benefits of biomass and phosphorus acquisition and mixed fungal inoculations enhanced nitrogen acquisition. Plant species significantly affected nitrogen acquisition but did not have an effect on biomass and phosphorus benefits. We concluded that AM fungal associations increased plant growth and nutrient absorption and that in general a mixed inoculation of AM fungi enhanced biomass and nutrient acquisition more than a single AM fungal inoculation. In addition, a mycorrhizal association was more beneficial for B. papyrifera seedlings in terms of biomass and nutrient acquisition than for B. pilosa seedlings.
Collar rot of chili (Capsicum annuum L.) is a very destructive disease caused by a soil-borne fungal pathogen Sclerotium rolfsii Sacc. Generally, chemical fungicides are used to combat the menace but this practice is being discouraged because of health and environmental concerns. In the present study, an alternative environment friendly strategy was used to manage this disease by using farmyard manure (FYM) and two commercial biofertilizers namely Biopower and Feng Shou. S. rolfsii inoculated pot soil was amended with 1% and 2% FYM and the two commercial biofertilizers. Inoculation of soil with S. rolfsii only (positive control) resulted in the highest disease incidence (73%) and plant mortality (60%). Biopower and Feng Shou application reduced disease incidence to 20% and 7%, respectively and plant mortality to 0%. Likewise, 1% and 2% FYM amendment reduced disease incidence to 33% and plant mortality to 26% and 7%, respectively. Under biotic stress of S. rolfsii, FYM and biofertilizers applications, either alone or in combination, significantly enhanced root and shoot growth over positive control. S. rolfsii inoculation significantly increased peroxidase and polyphenol oxidase activities in chili plants which were further increased by application of either of the two biofertilizers. The present study concludes that biofertilizers Biopower and Feng Shou alone or in combination with 2% FYM can be effectively utilized to manage southern blight of chili.