19672 research outputs found
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Synthesis and characterization of karaya gum-g- poly (acrylic acid) hydrogels and in vitro release of hydrophobic quercetin
No full textInterest in the development of new materials based on natural polysaccharides has grown exponentially in the last decade. Therefore, polysaccharide hydrogels gain striking attention having unique properties. In this study, karaya gum polysaccharide hydrogels have been synthesized using free radical mechanism. In this mechanism, ammonium persulfate (APS) was used as an initiator to form free radicals of karaya gum and acrylic acid while N, N′-methylenebisacrylamide (MBA) was used to crosslink these radicals. The synthesized hydrogels were characterized in terms of structure and properties. The structural evaluation was performed using different techniques. The vanishing of existing and appearance of new functional groups were analyzed using Fourier transform infrared (FTIR) analysis. The physical state of the hydrogel was evaluated using X-ray diffraction analysis while thermal stability and formation of hydrogels were further confirmed using Differential scanning calorimetry (DSC). The morphology study was conducted using Field emission scanning electron microscope (FESEM). Furthermore, mechanical properties of hydrogels were investigated using rheometer and swelling properties were evaluated in water and buffer solutions of pH 7.4 and pH 1.2. Hydrophobic drug loading and structural stability of drug after drug loading are the major challenges in the drug delivery. Hydrophobic drug quercetin was loaded, and in vitro release studies were conducted. The quercetin release showed complete non-Fickian transport mechanism. All these results revealed the successful synthesis of hydrogels and potential applications of hydrogels in hydrophobic drug delivery
An Improved Wearable Resonant Wireless Power Transfer System for Biomedical Capsule Endoscope
No full textMagnetic resonant-based wireless power transfer system (WPTS) is an efficient way to energize critical biomedical devices, such as wireless capsule endoscopes, where a direct wire connection is not practical. However, low power transfer efficiency (PTE) and poor received power stability (RPS) are usually the main bottlenecks of WPTS in this application. Thus, this paper proposes an efficient WPTS that tremendously improves the PTE and enriches the RPS. In order to improve the PTE, an optimum three-coil inductive link is adopted with a compact wearable power transmitting coil-I (PTC-I) and a 2-3D power receiving coil. As a result, the stability is improved with the new configuration of the power transmission coil-III (PTC-III) and power combining technique at the receiving side. To confirm the validity of the proposed design, proof-of-concept prototypes were implemented for an experimental test. Results obtained from the experimental test assured that the proposed PTC-I-based system achieved a PTE of more than 8% while transferring 758 mW of power with 68.7% RPS. The best overall RPS attained by the proposed PTC-III based system is 79.2%. This system achieved a PTE of 5.4% transferring at least 570 mW of power. In comparison, the performance of the proposed designs greatly outweighs the previous designs
Gene expression profile of marine Chlorella strains from different latitudes: stress and recovery under elevated temperatures
No full textGlobal warming, as a consequence of climate change, poses a critical threat to marine life, including algae. Studies on algal response at the molecular level to temperature stress have been significantly improved by advances in omics technologies. Algae are known to employ various strategies in response to heat stress. For example, algae regulate starch synthesis to provide energy for the cell or rebuild the damaged subunits of photosystems to regain photosynthetic activity. The aim of the present study is to examine the expression of selected photosynthesis-related genes of marine Chlorella originating from different latitudes, in response to heat stress and during the recovery period. In this study, marine Chlorella strains from the Antarctic, temperate region, and the tropics were grown at their ambient and stress-inducing temperatures. The maximum quantum efficiency (F v /F m ) photosynthetic parameter was used to assess their stress levels. When subjected to heat stress, the F v /F m began to decline and when it reached ~ 0.2, the cultures were transferred to their respective ambient temperature for recovery. Total RNA was isolated from these cultures at F v /F m ~ 0.4, 0.2, and when it regained 0.4 during recovery. The expression of four genes including psbA, psaB, psbC, and rbcL was analyzed using RT-PCR. The housekeeping gene, histone subunit three (H3) was used for data normalization. Studying the genes involved in the adaptation mechanisms would enhance our knowledge on algal adaptation pathways and pave the way for genetic engineers to develop more tolerant strains
Transient receptor potential vanilloid 4 (TRPV4) expression on the nerve fibers of human dental pulp is upregulated under inflammatory condition
No full textObjective: Transient receptor potential vanilloid 4 (TRPV4) has been considered as a mechano-, thermo- and osmo-receptor. Under inflammatory conditions in dental pulp, teeth can become sensitive upon exposure to a variety of innocuous stimuli. The objective of the present study was to investigate the expression of the TRPV4 channel on nerve fibers in human dental pulp of non-symptomatic and symptomatic teeth associated with inflammatory conditions. Design: Dental pulp from extracted human permanent teeth was processed for fluorescence immunohistochemistry. Ten asymptomatic (normal) and 10 symptomatic (symptoms associated with pulpitis) teeth were used in this study. Nerve fibers were identified by immunostaining for a marker, protein gene product 9.5, and the cells were counterstained with 4′,6-diamidino-2-phenylindole. An anti-TRPV4 antibody was used to trace TRPV4 expression. Results: TRPV4 expression was co-localized with the nerve fiber marker. Immunoreactivity for TRPV4 was more intense (p < 0.05) in the nerves of symptomatic teeth than those of normal teeth. The number of co-localization spots was increased significantly (p < 0.05) in the dental pulp of symptomatic teeth compared with that of asymptomatic (normal) teeth. Conclusions: There is expression of TRPV4 channels on the nerve fibers of human dental pulp. Our findings suggest upregulation of TRPV4 expression under inflammatory conditions in the pulp. The upregulation of TRPV4 channels may be associated with the exaggerated response of dental pulp to innocuous mechanical, thermal and osmotic stimuli under inflammatory conditions
Developing a maturity model for government community broadband projects
No full textBroadband technology is the latest information and communication technologies (ICT) deployed to address the digital divide phenomenon, especially the divide between the urban and rural areas. Governments all over the world have initiated programs and projects to enabled people in the rural areas to have fast internet access enjoyed by the urban areas. Anecdotal evidence, however, suggests that these programs and projects enjoy different rates of success that requires identification of their reasons. Hence, this study attempts to develop a maturity model for government community broadband projects. This maturity model determines the more successful projects and the reasons for their success compared to the less successful ones. Findings from this study will inform governments who are in the midst of implementing a community broadband project or who are planning to do so
The apoptotic effects of <em>Brucea javanica</em> fruit extract against HT29 cells associated with p53 upregulation and inhibition of NF-κB translocation
No full textBackground: Brucea javanica (L.) Merr. is a plant from the genus Brucea, which is used in local traditional medicine to treat various diseases. Recent studies revealed an impressive anticancer efficiency of B. javanica extract in different types of cancer cells. Purpose: In this study, we have investigated the cytotoxic effects of the B. javanica hexane, ethanolic extracts against colon cancer cells. HT29 colon cells were selected as an in vitro cancer model to evaluate the anticancer activity of B. javanica ethanolic extract (BJEE) and the possible mechanisms of action that induced apoptosis. Methods: 3-(4,5-dimethylthiazol-2-yl)-2, 5,-diphenyltetrazolium bromide (MTT), lactate dehydrogenase, acridine orange/propidium iodide, and annexin-V-fluorescein isothiocyanate assays were performed to determine the antiproliferative and apoptosis validation of BJEE on cancer cells. Measurement of reactive oxygen species (ROS) production, caspase activities, nucleus factor-κB activity, and gene expression experiments was done to investigate the potential mechanisms of action in the apoptotic process. Results: The results obtained from this study illustrated the significant antiproliferative effect of BJEE on colorectal cancer cells, with a concentration value that inhibits 50% of the cell growth of 25±3.1 µg/mL after 72 h of treatment. MTT assay demonstrated that the BJEE is selectively toxic to cancer cells, and BJEE induced cell apoptosis via activation of caspase-8 along with modulation of apoptosis-related proteins such as Fas, CD40, tumor necrosis factor-related apoptosis-inducing ligands, and tumor necrosis factor receptors, which confirmed the contribution of extrinsic pathway. Meanwhile, increased ROS production in treated cells subsequently activated caspase-9 production, which triggered the intrinsic pathways. In addition, overexpression of cytochrome-c, Bax, and Bad proteins along with suppression of Bcl-2 illustrated that mitochondrial-dependent pathway also contributed to BJEE-induced cell death. Consistent with the findings from this study, BJEE-induced cancer cell death proceeds via extrinsic and intrinsic mitochondrial-dependent and -independent events. Conclusion: From the evidence obtained from this study, it is concluded that the BJEE is a promising natural extract to combat colorectal cancer cells (HT29 cells) via induction of apoptosis through activation of extrinsic and intrinsic pathways
Template-assisted growth of nanoporous VTTBNc films: Morphology and moisture sensitivity studies
No full textA novel structured of nanoporous vanadyl 2,11,20,29-Tetra Tert-Butyl 2,3 Naphthalocyanine (VTTBNc) films were prepared by template-assisted method. The structure and morphology of the fabricated VTTBNc nanostructures were studied by field emission scanning electron microscopy (FESEM) and micro-Raman spectroscopy. The VTTBNc nano-porous films showed a potential application in humidity sensors
Effect of thermocycling on the compressive strength of selected luting cements
No full textIntroduction: The purpose of this in vitro study was to evaluate the effect of thermocycling on the compressive strength of selected luting cements. Material and methods: 5 types of luting cements were tested. A total of thirty cylindrical specimens measuring 6mm in height and 4mm in diameter were prepared for each type of cement which were then divided into two groups ie Group 1: Exposure, and Group 2: Control. Both groups were stored in distilled water at 37°C for 24 hours. Group 1 was subjected to 500 cycles in a thermocycling baths of 5°C and 55°C with 20 seconds in each bath. Group 2 was not exposed to thermocycling procedure. The compressive strength for each cement type was determined by using a universal testing machine. Results: Resin adhesive cement had the highest compressive strength; followed by conventional glass ionomer cement (GIC) whilst resin modified GIC was the least. Thermocycling had no significant effect on the compressive strength of RelyX™ ARC and Fuji I (p > 0.05), but a significant effect on Fuji I CAPSULE, Fuji CEM, Fuji Plus CAPSLUE (p < 0.05) was observed. Conclusion: The effect of thermocycling on the compressive strength of luting cements differed considerably with respect to their chemical compositions
Understanding ageing: fear of chronic diseases later in life
No full textObjectives: Ageing is often associated with deteriorating mental and physical health and the need for long-term care, creating a fear of ageing. We investigated what people fear most in terms of disabling chronic diseases and their concerns regarding having long-term illnesses. Methods: Data were obtained from an online survey of 518 respondents aged 40 years and older residing in Malaysia, which was based on a convenience sample collected in May 2015 to January 2016. Data were analyzed using chi-squared tests and multinomial logistic regression. Results: Of the most dreaded diseases, heart disease and cancer are life-threatening; however, dementia, diabetes, and hypertension persist and have a disabling effect for a long time. While there were variations in the diseases feared most across sex, ethnicity, and place of residence, the biggest worry for all respondents with regard to having a long-term illness was that they would become a burden to their family, a concern that superseded fear of dying. Conclusions: We found our survey respondents had a fear of chronic diseases and placing a burden on others. Thus, there is a need to provide motivation for people to adopt a healthy lifestyle, to remain healthy
A 0.079 mm2 2.1-to-4.2 GHz ring-VCO employing programmable current topology
No full textPurpose: The purpose of this work in designing a wideband ring voltage-controlled oscillator (VCO) based on programmable current topology. It occupies a very tiny area yet achieving a good phase noise performance, which is suitable to be implemented in cost-effective and wideband frequency synthesizers. Design/methodology/approach: The tuning range and gain are improved by dividing the VCO tuning curve into multiple curves controlled by programmable current sources without introducing additional parasitic capacitance. Findings: Fabricated in 130-nm standard complementary metal oxide semiconductor technology and occupying an area of 0.079 mm2, the VCO is tunable from 2.05 to 4.19 GHz, with a tuning percentage of 68.5 per cent. The VCO measures a phase noise performance of −96.7 dBc/Hz at an offset of 1 MHz from a 4.19 GHz carrier while consuming an average current of 6.5 mA, achieving figure of merit (FoM) and FoMT of −158.9 and −175.6 dBc/Hz, respectively. Originality/value: The proposed design uses programmable current topology without introducing parasitic capacitance, hence achieving wideband operation. It also occupies a tiny area and achieves a good phase noise performance