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Analysis of the eight parameter variation of the resonant tunneling diode (RTD) in the rapid thermal annealing process with resistance compensation effect
No full textThe rapid thermal annealing process is a key technology to control the parameters of the resonant tunneling diode (RTD) and to achieve high performance for the device. In this paper, the rapid thermal annealing process on the planar RTD has been investigated experimentally. In the experiment, the annealing sample chips of different annealed times have been recorded from the annealing equipment and their I-V characteristics have been measured accordingly. From the I-V characteristics, the negative resistance and the series resistance of the RTD can be obtained. Thus, the relationship between these parameters and annealing time can be established. Finally, by analyzing the concept of the resistance compensation effect, this study explains fully and in detail the dependency of the RTD parameter variation on the annealing time. VP and Vi are significantly reduced, greatly lowering RS, which in return also reduces the heat loss of the circuit and the power consumption of the RTD digital circuits as well as the RTD terahertz oscillator. As VV decreases, negative resistance RN is increased, and thus, the output power of the RTD terahertz oscillator is increased. These results are very useful in the study of RTD devices and fabrication technology. © 2020 Author(s)
A comparative study of the Malaysian Garden Concept (MGC) criteria application on the public parks
No full textToday there are public parks that are named with the Malaysian Garden. Researchers need to determine whether the design of the public parks is following the MGC guidelines provided by the National Landscape Department. Public parks that use the name of the Malaysian Garden / "Taman Malaysia" will be an example of MGC gardens. The main objective of this study is to find out the level of use of MGC criteria in public parks that have used the Malaysian Garden as its name. In this paper, researchers have used qualitative methods, namely, observation and interview experts. The results of the study found that the application of MGC criteria is placed in the weak category. However, three main factors are the cause of non-compliance with the MGC criteria. Furthermore, this study has explained to us the criteria that underlie the design of the MGC. © 2020 SERSC
Doxorubicin Loading on Functional Graphene as a Promising Nanocarrier Using Ternary Deep Eutectic Solvent Systems
No full textThe application of graphene in the field of drug delivery has attracted massive interest among researchers. However, the high toxicity of graphene has been a drawback for its use in drug delivery. Therefore, to enhance the biocompatibility of graphene, a new route was developed using ternary natural deep eutectic solvents (DESs) as functionalizing agents, which have the capability to incorporate various functional groups and surface modifications. Physicochemical characterization analyses, including field emission scanning electron microscope, fourier-transform infrared spectroscopy, Raman spectroscopy, Brunauer-Emmett-Teller, X-ray diffraction, and energy dispersive X-ray, were used to verify the surface modifications introduced by the functionalization process. Doxorubicin was loaded onto the DES-functionalized graphene. The results exhibited significantly improved drug entrapment efficiency (EE) and drug loading capacity (DLC) compared with pristine graphene and oxidized graphene. Compared with unfunctionalized graphene, functionalization with DES choline chloride (ChCl):sucrose:water (4:1:4) resulted in the highest drug loading capacity (EE of 51.84% and DLC of 25.92%) followed by DES ChCl:glycerol:water (1:2:1) (EE of 51.04% and DLC of 25.52%). Following doxorubicin loading, graphene damaged human breast cancer cell line (MCF-7) through the generation of intracellular reactive oxygen species (>95%) and cell cycle disruption by increase in the cell population at S phase and G2/M phase. Thus, DESs represent promising green functionalizing agents for nanodrug carriers. To the best of our knowledge, this is the first time that DES-functionalized graphene has been used as a nanocarrier for doxorubicin, illustrating the potential application of DESs as functionalizing agents in drug delivery systems. © 2020 American Chemical Society
Potentiating the anti-cancer profile of tamoxifen-loaded graphene using deep eutectic solvents as functionalizing agents
No full textDeep eutectic solvents (DES) are an alternative to conventional functionalizing agents. These neoteric functionalizing agents have been reported to improve the dispersibility and biocompatibility of graphene in the cellular environment. DES-functionalized graphene also has significantly greater tamoxifen (TAM)-loading capacity than non-functionalized graphene. Therefore, this study investigated the anti-cancer properties of TAM-loaded graphene against cancerous cells. TAM-loaded, DES-functionalized graphene showed a significant increase in anti-cancer activity, especially in the case of DES ChCl:fructose (2:1), as validated by cell viability, reactive oxygen species, and cell cycle progression assays. The cytotoxicity profile of TAM-loaded graphene against cancerous cells was confirmed by real-time cell growth analysis. Across all tested cellular kinetic models, the most significant reduction in the growth rate constant of cancerous cells was obtained using graphene functionalized with DES ChCl:fructose (2:1). All told, DES-functionalized graphene demonstrated improved anti-cancer activity compared to non-functionalized graphene. © 2019, King Abdulaziz City for Science and Technology
Non-monophyly and cryptic lineages between two morphoforms of Megalurothrips usitatus (Thysanoptera: Thripidae) in Peninsular Malaysia: Insights from morphological and molecular data
No full textThe DNA barcode data revealed two lineages of M. usitatus. Lineage I, consisted of the typical M. usitatus morphoform ‘a’ from the field collected and laboratory reared specimens, and the reference sequences from the GenBank whereas Lineage II consisted of both M. usitatus morphoforms ‘a’ and ‘b’ from the field collected specimens. The interspecific distances between both lineages ranged from 8.78 to 9.63%, suggesting the presence of cryptic and non-monophyly lineages between two morphoforms of M. usitatus in Peninsular Malaysia. © 2020 Korean Society of Applied Entomolog
A New Approach for Estimating Insulation Condition of Field Transformers Using FRA
No full textFrequency response analysis (FRA) is a tool for evaluating mechanical integrity of transformer's core and winding. However, several studies have reported that FRA is also sensitive to other parameters such as temperature, moisture content and presence of oil. Since some of these parameters are critical in the insulation degradation process, it is interesting to further investigate the possibility of using FRA for insulation assessment. In this paper, the insulation conditions of three field transformers are investigated using FRA. This is performed after statistical analysis on the response suggested no mechanical damage on the transformers. The responses are further analyzed to determine the percentage of change of winding capacitance. This is achieved by comparing resonance frequencies between the responses. The percentage of change represents the amount of degradation in the insulation. This is because as the insulation condition degrades, the response is shifted towards lower frequencies. This new investigation demonstrates the applicability of FRA to estimate the insulation degradation. © 2020 AECE
Survival analysis of osteosarcoma patients: A 15-year experience
No full textIntroduction: Management of osteosarcoma has evolved considerably for the past two decades and there have been changes of practices especially pertaining to chemotherapy regime. This is a review of our cases in the past 15 years. Method: This is a retrospective survival analysis study of 128 patients treated at University Malaya Medical Centre (UMMC) from 1997 to 2011. Results: There were 80 (62.5%) male and 48 (37.5%) female patients with the median age being 15 (5–59). Majority had osteosarcoma of extremities (94.5%). More than 60% patients developed metastasis throughout the course of treatment with 39% presenting with lung metastasis. Osteoblastic osteosarcoma was the commonest subtype (65.6%). Of the 109 patients treated surgically, 84 patients (65.6%) underwent limb salvage surgery while the rest underwent amputation. Seventy-one per cent of patients completed treatment with local recurrence rate of 22.7%. The 5-year and 10-year survival rates were 56.31% (95% CI: 46.20, 65.24) and 22.33% (95% CI: 14.86, 30.76), respectively. The 5-year event-free survival was 52.94% (95% CI: 41.83, 62.87). In multivariate analysis, the independent prognostic factors were presence of metastasis and completion of treatment for both 5-year and 10-year overall survival. Good histological response was only significant for multivariate analysis at 5 years. Patients with metastasis had a hazard ratio of 20.4 at 5 years and 3.26 at 10 years. Conclusion: Overall survival rate for osteosarcoma patients at our centre was comparably higher than other centres in the region. Two independent risk factors for survival are metastatic status and completion of treatment. A standardized chemotherapy regime is essential for long-term survival. © The Author(s) 2020
Lightweight authentication technique for secure communication of edge/fog data-centers
No full textEdge computing has significantly enhanced the capabilities of cloud computing. Edge data-centres are used for storing data of the end-user devices. Secure communication between the legitimate edge data-centres during the load balancing process has attracted industrial and academic researchers. Recently, Puthal et al. have proposed a technique for authenticating edge datacenters to enable secure load balancing. However, the resource-constraint nature of the edge data-centres is ignored. The scheme is characterized by complex computation and memory intensive cryptographic protocol. It is also vulnerable to key escrow attack because the secret key used for encrypting and decrypting of the communicated messages is been created by the trusted cloud datacenter. Additionally, the key sharing phase of their algorithm is complex. Therefore, to address the highlighted challenges, this paper proposed a lightweight key escrow-less authentication algorithm that will ensure secure communication of resource-constrained edge data-centres during the load balancing process. The security capability of the proposed scheme has been formally evaluated using the automatic cryptographic analytical tool ProVerif. The relatively low computation and communication costs of the proposed scheme compared to the benchmark schemes proved that it is lightweight, thus suitable for resource-constrained edge datacenters. © 2020 SERSC
Systematic Review on Security and Privacy Requirements in Edge Computing: State of the Art and Future Research Opportunities
No full textEdge computing is a promising paradigm that enhances the capabilities of cloud computing. In order to continue patronizing the computing services, it is essential to conserve a good atmosphere free from all kinds of security and privacy breaches. The security and privacy issues associated with the edge computing environment have narrowed the overall acceptance of the technology as a reliable paradigm. Many researchers have reviewed security and privacy issues in edge computing, but not all have fully investigated the security and privacy requirements. Security and privacy requirements are the objectives that indicate the capabilities as well as functions a system performs in eliminating certain security and privacy vulnerabilities. The paper aims to substantially review the security and privacy requirements of the edge computing and the various technological methods employed by the techniques used in curbing the threats, with the aim of helping future researchers in identifying research opportunities. This paper investigate the current studies and highlights the following: (1) the classification of security and privacy requirements in edge computing, (2) the state of the art techniques deployed in curbing the security and privacy threats, (3) the trends of technological methods employed by the techniques, (4) the metrics used for evaluating the performance of the techniques, (5) the taxonomy of attacks affecting the edge network, and the corresponding technological trend employed in mitigating the attacks, and, (6) research opportunities for future researchers in the area of edge computing security and privacy. © 2013 IEEE
The impact of high frequency oscillatory ventilation on mortality in paediatric acute respiratory distress syndrome
No full textBackground: High-frequency oscillatory ventilation (HFOV) use was associated with greater mortality in adult acute respiratory distress syndrome (ARDS). Nevertheless, HFOV is still frequently used as rescue therapy in paediatric acute respiratory distress syndrome (PARDS). In view of the limited evidence for HFOV in PARDS and evidence demonstrating harm in adult patients with ARDS, we hypothesized that HFOV use compared to other modes of mechanical ventilation is associated with increased mortality in PARDS. Methods: Patients with PARDS from 10 paediatric intensive care units across Asia from 2009 to 2015 were identified. Data on epidemiology and clinical outcomes were collected. Patients on HFOV were compared to patients on other modes of ventilation. The primary outcome was 28-day mortality and secondary outcomes were 28-day ventilator- (VFD) and intensive care unit- (IFD) free days. Genetic matching (GM) method was used to analyse the association between HFOV treatment with the primary outcome. Additionally, we performed a sensitivity analysis, including propensity score (PS) matching, inverse probability of treatment weighting (IPTW) and marginal structural modelling (MSM) to estimate the treatment effect. Results: A total of 328 patients were included. In the first 7 days of PARDS, 122/328 (37.2%) patients were supported with HFOV. There were significant differences in baseline oxygenation index (OI) between the HFOV and non-HFOV groups (18.8 [12.0, 30.2] vs. 7.7 [5.1, 13.1] respectively; p < 0.001). A total of 118 pairs were matched in the GM method which found a significant association between HFOV with 28-day mortality in PARDS [odds ratio 2.3, 95% confidence interval (CI) 1.3, 4.4, p value 0.01]. VFD was indifferent between the HFOV and non-HFOV group [mean difference - 1.3 (95%CI - 3.4, 0.9); p = 0.29] but IFD was significantly lower in the HFOV group [- 2.5 (95%CI - 4.9, - 0.5); p = 0.03]. From the sensitivity analysis, PS matching, IPTW and MSM all showed consistent direction of HFOV treatment effect in PARDS. Conclusion: The use of HFOV was associated with increased 28-day mortality in PARDS. This study suggests caution but does not eliminate equivocality and a randomized controlled trial is justified to examine the true association. © 2020 The Author(s)