19672 research outputs found
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Polarization dependence of SU-8 micro ring resonator
No full textThis work describes the polarization study in the optical micro ring resonator systems. The use of polymeric materials for micro ring resonator structures recently has gained major interests due to many advantages such as enabling a rapid and straightforward fabrication process. Here we report a demonstration of an optical micro ring resonators comprised of polymer material, namely SU-8. We have shown the effects of the polarizations induced by the micro ring resonator waveguide on the spectral frequency response experimentally with respect to the changes of the polarization states as ellipticity and azimuth states. The effects can be detrimental, or these can be exploited for new devices. For both throughput and drop ports of the micro ring resonator, the highest variation of Q factor occurs in azimuth polarization state. The variation of the free spectral range induced by changing the polarization state at the drop and throughput ports is in the range of 0.2–0.65 nm and 0.2–0.75 nm respectively. Furthermore, the throughput port has experienced the highest finesse at the ellipticity polarization state. The significant wavelength shift has occurred in the drop port at the wavelength 1600 nm with azimuth polarization state. Besides, the throughput port has experienced a wavelength shift incurred by both azimuth and ellipticity states. Our results have demonstrated that low-cost photonics devices made from polymers are possible alternatives for next-generation photonics
Synthesis, characterization and catalytic activity of melamine immobilized MCM-41 for condensation reactions
No full textIn the present study, melamine immobilized MCM-41 is synthesized by grafting on modified MCM-41. The surface area, pore size and pore volume of MCM-41-Mela were found to be decreased after immobilization of melamine. FTIR and Raman spectroscopy results revealed the successful grafting of melamine on the surface of MCM-41. The 29Si CP/MAS NMR of MCM-41-Mela showed the existence of T2, T3, Q3 and Q4 silicon centres. The catalytic activities were investigated through a liquid phase Knoevenagel condensation reaction between furfural and acetylacetone. A conversion of 93.1% was achieved with 100% selectivity towards 3-(2-furylmethylene)-2,4-pentanedione (FMP) under solvent-free condition. The catalytic activity of MCM-41-Mela was then successfully carried out for Knoevenagel condensation with different substrates, giving excellent yields of the corresponding products. The catalyst was easily regenerated and could be reused for three times without loss of catalytic activity. Simple preparation methods, high efficiency and reusability of the heterogeneous MCM-41-Mela catalyst demonstrate a great potential for future catalysis application
Fast and slow light generated by surface plasmon wave and gold grating coupling effects
No full textWe present here the results of a simulation of the effect of gold and graphene coatings on silicon micro-ring resonators. We studied the effect of different radii of graphene on the time delay, from which one an interesting aspect of light pulse behaviors, such as fast light, was numerically investigated. The obtained results indicate that the time delay can be varied, which is in good agreement with theoretical predictions. Fast and slow light pulse trains can be obtained by modifying the throughput port, which forms the gold grating length. The temporal gaps between the fast and slow light in the used graphene and gold are 140 and 168 fs, respectively, which can be tuned by varying the radius or grating length. The obtained results show that such a device may be useful in applications requiring fast and slow light pulse train pairs, such as optical switching, sensors, communications, and security applications
"Gatekeeper or crisis manager? Coverage of "Lahad Datu" conflict"
No full textLahad Datu conflict also known as "Sabah standoff" conflict, is unforgettable tragedies until killed about 10 of Malaysian security personnel and impacted economic, social and emotion of citizens especially at Lahad Datu, Sabah. The objective of this research is to examine the portrayal of solution from Malaysian Government for the "Lahad Datu Crisis" through newspaper framing in Malaysian mainstream newspapers namely Utusan Malaysia, The Star, Sin Chew and Nanban daily. The measurement for the crisis response will be measure through few independent variables such as category of "Lahad Datu" news; between problem, solution, people or neutral category. The following independent variable is through the slants of news; whether news is slanted in positive, negative or neutral slant. With the assistance of "Situational Crisis Communication Theory", this research employed a systematic quantitative content analysis to gather the data. Finding revealed that, category of solution appeared most in Utusan Malaysia, The Star, Sin Chew and Nanban daily and news in positive slants were covered in all the selected dailies. In providing responses for the crisis, Justification and Concern crisis response portrayed most, however, through Kruskal Wallis test, data found that The Star and Utusan Malaysia portrayed most of the Justification and Concern responses compare to Sin Chew daily and Nanban daily
PVDF-co-HFP/superhydrophobic acetylene-based nanocarbon hybrid membrane for seawater desalination via DCMD
No full textSurface hydrophobicity is the most desirable characteristic for high DCMD performance. Superhydrophobic carbon nanomaterials/powder activated carbon (CNMs/PAC) has unique properties and believed to be the proper candidate to increase the membrane hydrophobicity with maintaining good mechanical properties and high porosity at the same time. In this work, we introduce a phase inversion process based on central composite design, aimed at minimizing the number of experiments required for membrane fabrication. The hydrophobic membrane fabrication conditions are modeled as independent parameters, with the flux provided as the model response. The analyses performed on the membrane structure and surface, as well as its mechanical properties revealed that the superhydrophobic CNMs/PAC significantly enhances the hydrophobicity of the composite membrane surface. The accuracy measurements obtained by analysis of variance showed that the model developed and all the proposed parameters have significant effects on the flux. However, the CNMs/PAC emerged as the most significant influential factor and interacted with polymer concentration and casting knife thickness to exert effects on the permeate flux. The optimum preparation parameters were 775.21 mg carbon loading, PVDF-HFP concentration of 21.86 g and casting knife thickness of 118.93 μm, as these values yield the highest flux of about 102 kg/m2h
Multiplex polymerase chain reaction-restriction fragment length polymorphism assay discriminates of rabbit, rat and squirrel meat in frankfurter products
No full textThe demands for rabbit meat are rapidly growing and Rabbitry is becoming a mean of livelihood for many youths. Rats and squirrels are very close relatives of rabbits, could be hunted freely or raised in domestic farming and so could be substituted in expensive rabbit meat. This study, for the first time, developed and validated a tetraplex polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay to identify and discriminate rabbit, rat and squirrel meat under raw and processed foods. Four sets of primes amplified 123, 108, 243, and 141 bp fragments from rabbit, rat, squirrel and all eukaryotes, respectively. Specificity was confirmed through sequencing and RFLP analysis. When PCR products were digested with BtsIMutI and BtsCI enzymes, distinctive fingerprints (115 & 8 bp for rabbit; 64 & 44 bp for rat and 176 & 67 bp for squirrel) were obtained. The detection limit of the assay was 0.1% meat in frankfurter formulation
A pilot study on the effects of direct contact of two different surgical burs on the cadaveric lingual nerve
No full textThe lingual guttering technique for third molar surgery carries the risk of injury to the lingual nerve if the surgical bur comes into direct contact with it. This study investigated the extent of nerve injury caused by two different burs, a tungsten carbide bur and the Dentium implant bur; the latter is designed to be soft tissue friendly. This study also examined whether ultrasound and magnetic resonance imaging are able to detect any injury inflicted. This cadaveric research involved subjecting 12 lingual nerves to the drilling effect of two different burs at two different speeds. The amount of damage caused was measured using different imaging modalities to assess their ability to detect the injury inflicted. At high speed, the Dentium bur caused a deeper and wider laceration than the carbide bur. At low speed, the laceration depths and widths caused by the two burs did not differ significantly. Ultrasound scanning was able to detect the nerve laceration at damaged sites observed using optical coherence tomography. Thus, a carbide bur (at low speed) would be preferable for lingual bone guttering, as it causes less laceration to the lingual nerve. In the event of a suspected injury, ultrasound scanning would provide an objective evaluation of the amount of nerve damage in vivo
Performance Analysis of Personal Cloud Storage Services for Mobile Multimedia Health Record Management
No full textRecently, the trend of mobile multimedia services and applications being used for e-health is growing in popularity. This is because people can get access to their electronic personal health records (PHRs), such as medical history, lab reports from an X-ray, MRI, clinical audio-visual notes, EEG/ECG data, and insurance policy details from anywhere, at any time, from their mobile or handheld devices. In this scenario, a medical care provider or a patient is responsible for uploading and managing the patient's health information via cloud storage services. There are a number of personal cloud storage services that could be used such as Dropbox, Google Drive, OneDrive, and Box. However, the different designs of these personal cloud storage services mean there are differences in their performance in terms of storing and managing PHRs. In this paper, we present the details of our study on the performance of personal cloud storage services, and we highlight the strengths and weaknesses of such services in terms of PHR management. We investigate the performance of personal cloud storage services by conducting a qualitative and quantitative analysis of them. The qualitative analysis highlights strengths and weaknesses in terms of supported capabilities/features and shortcomings in terms of potential features that have not been implemented. The capabilities we analyze are chunking, bundling, deduplication, delta-encoding, and data compression. In the quantitative analysis, we investigate performance in terms of control data overhead, impact of data size on number of packets as well as transmission rate, synchronization initialization time, and protocol overhead. During testing with diverse benchmark size on distinct cloud storage services, we attained an average transmission of 93%, 3%, and 4% for application data, control data, and other data, respectively. This research allows us to identify open issues and to determine future directions for developing an efficient personal cloud storage service
Dark Matter in the Central Region of NGC 3256
No full textWe investigated the central mass distribution of the luminous infrared galaxy NGC 3256 at a distance of 35 Mpc by using CO(1-0) observations of the Atacama Large Millimeter and sub-millimeter Array (ALMA) and near-IR data of the Two Micron Sky Survey (2MASS). We found that there is a huge amount of invisible dynamical mass (4.48 × 1010 ) in the central region of the galaxy. The invisible mass is likely caused by some dark matter, which might have a cuspy dark matter profile. We note that this dark matter is difficult to explain with the conventional Modified Newtonian Dynamics (MOND) model, which is only applicable at a low acceleration regime, whereas the acceleration at the central region of the galaxy is relatively strong. Therefore, this discovery might pose a challenge to the conventional MOND models
Push-Out Bond Strength of Experimental Apatite Calcium Phosphate Based Coated Gutta-Percha
No full textObjectives. To evaluate the push-out bond strength of experimental apatite calcium phosphate coated gutta-percha (HAGP) compared to different commercially available coated gutta-percha root obturation points. Methods. Extracted teeth were selected and instrumented using ProTaper rotary files. The canals were assigned into five equal groups and obturated using matching single cone technique as follows: EndoREZ cones and EndoREZ sealer, Bioceramic Endosequence gutta-percha (BCGP) with Endosequence BC sealer, Active GP with Endosequence BC sealer (ActiV GP), conventional GP with Endosequence BC sealer, and HAGP with Endosequence BC sealer. Each root was sectioned transversally at the thickness of 1±0.1 mm to obtain 5 sections (n=25 per group). The specimens were subjected to push-out test using a Universal Test Machine at a loading speed of 0.5 mm/ min. Failure modes after push-out test was examined under stereomicroscope and the push-out data were analyzed using ANOVA and the post hoc Dunnett T3 test (p = 0.05). Results. The highest mean bond strength was yielded by HAGP followed by BCGP, ActiV GP, conventional GP, and EndoREZ. There were significant differences between EndoREZ and all other groups (p<0.001). The prominent failure mode of HAGP was mixed mode, whereas EndoREZ exhibited adhesive failure mode. Conventional GP, ActiV GP, and BCGP showed cohesive failure mode. Conclusion. HAGP showed promising results to be used as root canal filling material in combination with bioceramic sealer