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Cellulose nanocrystal/graphene oxide composite film as humidity sensor
Kafy, A.,Akther, A.,Shishir, Md.I.R.,Kim, H.C.,Yun, Y.,Kim, J. Elsevier Sequoia 2016 Sensors and actuators. A Physical Vol.247 No.-
Cellulose nanocrystal/graphene oxide composite was reported as a humidity sensor in this study. The composite film was fabricated using simple blending the materials followed by oven drying. The composite film offers a unique advantages of cellulose combined with functionality of GO. It was capitalized to design renewable, flexible and cheap humidity sensor. Performance of the composite film as a humidity sensor was evaluated on the basis of relative capacitance change at different humidity level. Synthesized composite film was characterized using scanning electron microscope, Fourier transform infrared spectroscope, and X-ray diffraction. Environmental effect such as temperature was taken into account on the sensor performance. The sensing mechanism is explained on the basis of presence of hydrophilic functional groups in the composite. The linear and fast response of the developed sensor is advantageous.
Kafy, Abdullahil,Sadasivuni, Kishor Kumar,Kim, Hyun-Chan,Akther, Asma,Kim, Jaehwan The Royal Society of Chemistry 2015 Physical chemistry chemical physics Vol.17 No.8
<P>The demand for flexible energy storage devices is ever increasing, and several polymer nanocomposites are widely used to fabricate them. Here, we present a cellulose based nanocomposite by incorporating graphene oxide (GO) nanoplatelets modified with hexamethylene diisocyanate grafting agent useful for such versatile applications. The simple method of casting/solvent evaporation is applied to prepare the nanocomposites and GO dispersion in the cellulose matrix was analyzed by Fourier transform infrared spectroscopy, X-ray diffraction studies and scanning electron microscopy. The dielectric and ferroelectric properties of the eco-friendly samples were checked with temperature and voltage variations, which can attribute to flexible energy and memory storage properties. Thus, the cellulose modified GO nanocomposite has turned to be environmentally stable and excellent next generation material for energy storage and electronic devices.</P> <P>Graphic Abstract</P><P>The demand for flexible energy storage devices is ever increasing, and several polymer nanocomposites are widely used to fabricate them. <IMG SRC='http://pubs.rsc.org/services/images/RSCpubs.ePlatform.Service.FreeContent.ImageService.svc/ImageService/image/GA?id=c4cp05921b'> </P>
Akther, Asma,Kafy, Abdullahil,Zhai, Lindong,Kim, Hyun Chan,Shishir, MD Imrul Reza,Kim, Jaehwan IOP 2016 Smart materials & structures Vol.25 No.11
<P>This study deals with ultrasonic wave propagation on a piezoelectric polymer substrate for tactile actuator. On the piezoelectric polymer substrate, a pair of interdigital transductor (IDT) electrodes is patterned by lift-off process and a resonator is made by exciting the IDTs. A standing wave is generated between the pair of IDT electrodes, of which the wavelength matches with the distance between two IDTs. The standing ultrasonic waves can give different textures to the users. The wave propagation in this periodic structure on the polymer substrate is studied by harmonic and transient analysis. Vertical displacement and induced voltage at the output IDT electrode are calculated and the ultrasonic wave generation is experimentally verified. The proposed concept of tactile actuator based on ultrasonic wave is explained.</P>
A content-based analysis to identify the influence of COVID-19 on sharing economy activities
Sajid Amit,Abdulla - Al Kafy 대한공간정보학회 2022 Spatial Information Research Vol.30 No.2
Activities related to Sharing economy (SE) are in a vulnerable position globally due to the COVID-19 pandemic. SE businesses related to the transport and accommodation sectors are considered riskier than others, and the pandemic has only increased concerns. As such, assessing the COVID-19 pandemic’s impact on the SE is crucial. This study aims to identify the influence of COVID-19 on SE activities. Journal and news articles, blog posts, YouTube videos, and printed and televised news have been considered as data sources for this study. Using content analysis, the study showcases how SE activities are adjusting to the pandemic-induced business landscape. The study examined SE status from four stakeholders’ viewpoints— service providers (SPs), service receivers (SRs), SE firms, and regulatory bodies (RBs). The study’s findings suggest that the pandemic-induced lockdown significantly impacted job sectors, increased health risk, anxiety, reduced safety, and income for SE firms. SPs, and SRs worldwide are facing tremendous difficulties operating their activities, frequently changing guidelines to support SPs by financial assistance and SRs by standard services during the COVID-19. This study will help respective authorities and government organizations to determine the appropriate strategies for SE firms to advance their services during critical situations.
Saanjaana Rahman,Sajid Amit,Abdulla - Al Kafy 대한공간정보학회 2022 Spatial Information Research Vol.30 No.3
COVID-19 have deteriorated mental health conditions in Bangladesh. The study aims to examine the impact of COVID-19 on mental health conditions through the propensity score matching method and establish the relationship between telehealth usage on mental health improvement during the COVID-19 pandemic. Nearest neighbor matching approach has been used to match treatment unit to nearest comparison unit and achieved balance between treatment and control groups on observable traits. A cross-sectional study on 89 participants was conducted from April to June 2020. ATE (average treatment effect) & ATET (average treatment effect of treated) techniques were used. Logistic regression was used to examine the causal relationship between telehealth usage on mental health improvement. The coefficient of ATE on the population was - 0.026, stating that on average, participants with no past physical health problems had fewer mental health issues than the participants with a past physical health problem. The coefficient on ATET was - 0.034. The association between telehealth usage on mental health improvement was highly significant as p value = 0.00\0.05 with OR of 70 at 95% CI. There was strong evidence of positive mental health outcomes through telehealth usage during the pandemic. Experts should develop sustainable adaptations of mental healthcare delivery systems in this field to mitigate the disparities in healthcare provision.
Abdullah-Al- Faisal,Abdulla - Al Kafy,Md. Abdul Fattah,Dewan Md. Amir Jahir,Abdullah Al Rakib,Zullyadini A. Rahaman,Jannatul Ferdousi,Xiao Huang 대한공간정보학회 2022 Spatial Information Research Vol.30 No.3
Dhaka is subjected to high pollution levels throughout the year, holding some relatively high amounts of pollution readings, making its air unhealthy to breathe. The study examined hourly, shifting, seasonal fluctuations in particulate matter (PM2.5), the effects of seasonal meteorological variables, and the lockdown effect over the megacity of Dhaka from 2019 to 2021 using data from AirNow. The results indicate the daily average PM2.5 concentration between 2019 and 2021 was 112.49 lg/m3, about four times higher than the WHO limit and two times higher than the Bangladesh standard. Daily PM2.5 concentrations was high during morning and evening pick-up hours, reaching a maximum hourly concentration of 472.9 lg/m3 in February 2020. The maximum average PM2.5 concentration was 211.23 lg/m3 in March 2021 (winter season), and the lowest average was 27.58 lg/m3 in August 2020 (rainy season). The Pearson correlation coefficient (r) between the PM2.5 and meteorological variables were inverse with rainfall (- 0.62), temperature (- 0.73), humidity (- 0.82), but positive with wind (0.09). Daily average Air Quality Index (AQI) concentrations improved from 108.53 to 67.99 lg/m3 during the lockdown period. Finally, the study recommended many mitigation strategies that might assist accountable authorities in lowering the number of life-threatening components in the air.
Sajid Amit,Rezwana Karim,Abdulla - Al Kafy 대한공간정보학회 2022 Spatial Information Research Vol.30 No.5
Massive open online course (MOOC) is a relatively new concept in Bangladesh during the ongoing COVID 19 pandemic. This study aims to develop a MOOC to promote a conceptual understanding of diversity, tolerance and pluralism. In addition, this study investigates the findings of MOOC exercises based on a comparative study of the MOOC markets in India and Bangladesh. Factors like education market background, current government and non-government market leaders and existing startups were considered for assessing the comparison. In addition, prior to launching this MOOC in the Bangladesh market, the MOOC markets in the Asia Pacific region have been explored through extensive literature reviews. Although the EdTech markets of India and Bangladesh show promising developments and great potential, the lack of adequate infrastructure continues to be a major drawback. The experts shared their perspectives on developing more engaging academic materials through animation, illustrations, and video descriptions. Also, NGOs should be engaged to promote the course and reach the appropriate target market.