Valorization of lignocellulosic fibres of paper waste into levulinic acid using solid and aqueous Brønsted acid

Chen, Season S.,Wang, Lei,Yu, Iris K.M.,Tsang, Daniel C.W.,Hunt, Andrew J.,Jé,rô,me, Franç,ois,Zhang, Shicheng,Ok, Yong Sik,Poon, Chi Sun Elsevier 2018 Bioresource technology Vol.247 No.-

<P><B>Abstract</B></P> <P>This study aims to produce levulinic acid (LA) from paper towel waste in environment-friendly and economically feasible conditions, and evaluate the difference using solid and aqueous Brønsted acids. Direct dehydration of glucose to LA required sufficiently strong Brønsted acidity, where Amberlyst 36 demonstrated rapid production of approximately 30Cmol% of LA in 20min. However, the maximum yield of LA was limited by mass transfer. In contrast, the yield of LA gradually increased to over 40Cmol% in 1M H<SUB>2</SUB>SO<SUB>4</SUB> at 150°C in 60min. The SEM images revealed the conversion in dilute acids under microwave at 150°C resulting in swelling structures of cellulose, which were similar to the pre-treatment process with concentrated acids. Further increase in reaction temperature to 200°C significantly shortened the reaction time from 60 to 2.5min, which saved the energy cost as revealed in preliminary cost analysis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 30% of levulinic acid (LA) yielded from paper towel over Amberlyst 36 in 20min. </LI> <LI> Maximum yield of LA was comparable using dilute sulphuric acid at 150 and 200°C. </LI> <LI> Cellulose underwent swelling in dilute acid with microwave heating at 150°C. </LI> <LI> Conversion at 200°C shortened reaction time and reduced total energy consumption. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Chaotic Responses of Curved Plate under Sinusoidal Loading

W. Y. Poon,C. F. Ng,Y. Y. LEE 대한기계학회 2003 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.17 No.1

<br/> In the present investigation, the nonlinear dynamic buckling of a curved plate subjected to sinusoidal loading is examined. By the theoretical analyses, a highly nonlinear snap-through motion of a c1amped-free-c1amped-free plate and its effect on the overall vibration response are investigated. The problem is reduced to that of a single degree of freedom system with the Rayleigh-Ritz procedure. The resulting nonlinear governing equation is solved using Runge-­Kutta (RK -4) numerical integration method. The snap-through boundaries, which vary with different damping coefficient and linear circular frequency of the flat plate are studied and given in terms of force and displacement. The relationships between static and dynamic responses at the start of a snap-through motion are also predicted. The analysis brings out various<br/> characteristic features of the phenomenon, i.e. l) small oscillation about the buckled position-­softening spring type motion, 2) chaotic motion of intermittent snap-through, and 3) large oscillation of continuous snap-through motion crossing the two buckled positions-hardening spring type. The responses of buckled plate were found to be greatly affected by the snap­through motion. Therefore, better understanding of the snap-through motion is needed to predict the full dynamic response of a curved plate.<br/>

Phosphoric acid-activated wood biochar for catalytic conversion of starch-rich food waste into glucose and 5-hydroxymethylfurfural

Cao, Leichang,Yu, Iris K.M.,Tsang, Daniel C.W.,Zhang, Shicheng,Ok, Yong Sik,Kwon, Eilhann E.,Song, Hocheol,Poon, Chi Sun Elsevier 2018 Bioresource technology Vol.267 No.-

<P><B>Abstract</B></P> <P>The catalytic activity of engineered biochar was scrutinized for generation of glucose and hydroxymethylfurfural (HMF) from starch-rich food waste (bread, rice, and spaghetti). The biochar catalysts were synthesized by chemical activation of pinewood sawdust with phosphoric acid at 400–600 °C. Higher activation temperatures enhanced the development of porosity and acidity (characterized by COPO<SUB>3</SUB> and CPO<SUB>3</SUB> surface groups), which imparted higher catalytic activity of H<SUB>3</SUB>PO<SUB>4</SUB>-activated biochar towards starch hydrolysis and fructose dehydration. Positive correlations were observed between HMF selectivity and ratio of mesopore to micropore volume, and between fructose conversion and total acid density. High yields of glucose (86.5 Cmol% at 150 °C, 20 min) and HMF (30.2 Cmol% at 180 °C, 20 min) were produced from rice starch and bread waste, respectively, over H<SUB>3</SUB>PO<SUB>4</SUB>-activated biochar. These results highlighted the potential of biochar catalyst in biorefinery as an emerging application of engineered biochar.</P> <P><B>Highlights</B></P> <P> <UL> <LI> H<SUB>3</SUB>PO<SUB>4</SUB>-activated biochar catalyzed production of HMF (30.2%) and glucose (86.5%). </LI> <LI> HMF selectivity depended on ratio of mesopore to micropore volume of biochar. </LI> <LI> Biomass conversion was positively correlated to total acid density of biochar. </LI> <LI> Acidity originated from COPO<SUB>3</SUB> and CPO<SUB>3</SUB> surface groups of H<SUB>3</SUB>PO<SUB>4</SUB>-modified biochar. </LI> <LI> Engineered biochars are potential catalysts for biorefinery reactions. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Identification of nonlinear elastic structures using empirical mode decomposition and nonlinear normal modes

C.W. Poon,C.C. Chang 국제구조공학회 2007 Smart Structures and Systems, An International Jou Vol.3 No.4

The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.

Identification of nonlinear elastic structures using empirical mode decomposition and nonlinear normal modes

Poon, C.W.,Chang, C.C. Techno-Press 2007 Smart Structures and Systems, An International Jou Vol.3 No.4

The empirical mode decomposition (EMD) method is well-known for its ability to decompose a multi-component signal into a set of intrinsic mode functions (IMFs). The method uses a sifting process in which local extrema of a signal are identified and followed by a spline fitting approximation for decomposition. This method provides an effective and robust approach for decomposing nonlinear and non-stationary signals. On the other hand, the IMF components do not automatically guarantee a well-defined physical meaning hence it is necessary to validate the IMF components carefully prior to any further processing and interpretation. In this paper, an attempt to use the EMD method to identify properties of nonlinear elastic multi-degree-of-freedom structures is explored. It is first shown that the IMF components of the displacement and velocity responses of a nonlinear elastic structure are numerically close to the nonlinear normal mode (NNM) responses obtained from two-dimensional invariant manifolds. The IMF components can then be used in the context of the NNM method to estimate the properties of the nonlinear elastic structure. A two-degree-of-freedom shear-beam building model is used as an example to illustrate the proposed technique. Numerical results show that combining the EMD and the NNM method provides a possible means for obtaining nonlinear properties in a structure.

Wearable Intelligent Systems for E-Health

Poon, Carmen C.Y.,Liu, Qing,Gao, Hui,Lin, Wan-Hua,Zhang, Yuan-Ting Korean Institute of Information Scientists and Eng 2011 Journal of Computing Science and Engineering Vol.5 No.3

Due to the increasingly aging population, there is a rising demand for assistive living technologies for the elderly to ensure their health and well-being. The elderly are mostly chronic patients who require frequent check-ups of multiple vital signs, some of which (e.g., blood pressure and blood glucose) vary greatly according to the daily activities that the elderly are involved in. Therefore, the development of novel wearable intelligent systems to effectively monitor the vital signs continuously over a 24 hour period is in some cases crucial for understanding the progression of chronic symptoms in the elderly. In this paper, recent development of Wearable Intelligent Systems for e-Health (WISEs) is reviewed, including breakthrough technologies and technical challenges that remain to be solved. A novel application of wearable technologies for transient cardiovascular monitoring during water drinking is also reported. In particular, our latest results found that heart rate increased by 9 bpm (P < 0.001) and pulse transit time was reduced by 5 ms (P < 0.001), indicating a possible rise in blood pressure, during swallowing. In addition to monitoring physiological conditions during daily activities, it is anticipated that WISEs will have a number of other potentially viable applications, including the real-time risk prediction of sudden cardiovascular events and deaths.

Characterization of Alpha Beta Nitride in Buried Nitride SOI Substrate

Poon, M. C.,Kwong, S.,Wong, H. 대한전자공학회 1991 ICVC : International Conference on VLSI and CAD Vol.2 No.1

Buried nitride SOI substrates prepared using stationary beam synthesis have been characterized. Both α- and β- phae silicon nitride layers have been found to form in the SOI substrate under different implantation and anneling conditions. While both nitrides are found to have good material qualities, the α nitride is found to have better insulating property than the β nitride. As β nitride is first reported in buried nitride SOI and its formation is known to be more stringent than the α nitride, preliminary studies on the nitride formation kinetics will also be discussed.

The Development of Pre-Primary Services in Hong Kong : Quality Review as a Lever of Continuous School Improvement

Andrew C. S. Poon 육아정책연구소 2008 International Journal of Child Care and Education Vol.2 No.1

At present, early childhood education is not part of the universal and compulsory system of education in Hong Kong. All pre-primary services are run by non-profit-making institutions or private independent bodies in Hong Kong. The operation of pre-primary services is largely market driven. According to the organic system model, the development of pre-primary services in Hong Kong had gone through a period of stable development with self-managing institutions which have placed an emphasis on internal effectiveness in the early stages. Since 1997, the services have undergone changes that have been brought forth by the education reforms which hinted upon the interface effectiveness between the pre-primary services operators and the government. Taking effect from 2007, the pre-primary institutions experienced a period of enhanced development under the Pre-primary Education Voucher Scheme. This period stressed the importance of intraface effectiveness among the key stakeholders—parents, professionals and government. Upon the implementation of the education voucher scheme, a Quality Review system was poised to ensure the deliver of standards-based quality pre-primary services with a clear vision and sense of mission, performance indicators, as well as intended and expected outcomes. The Quality Review aimed to adopt a two-pronged approach based on internal quality assurances undertaken by School Self-evaluations and external school reviews. It can be argued that this represents the best way to improve standards through the collaborative efforts of pre-primary institutions and the government. All pre-primary institutions under the Scheme should be accountable to their stakeholders by optimizing the school data by perfecting their planning cycle through on-going process of self-evaluation, while the government should monitor the state of education at both the national and district levels. The Quality Review is the lever of change that has a direct bearing on the quality performance of pre-primary institutions, children’s learning and leadership issues at both the school and system levels.

Immune Protection Factor of Sunscreens in Humans is Dependent on Protection from UVA and Cannot by Predicted from the Sun Protection Factor

TerenceS.C.Poon,GaryM.Halliday,RossSt.C.Barnetson,DionaL.Damian 한국광과학회 2002 Journal of Photosciences Vol.9 No.2

Wearable Intelligent Systems for E-Health

Carmen C. Y. Poon,Qing Liu,Hui Gao,Wan-Hua Lin,Yuan-Ting Zhang 한국정보과학회 2011 Journal of Computing Science and Engineering Vol.5 No.3

Due to the increasingly aging population, there is a rising demand for assistive living technologies for the elderly to ensure their health and well-being. The elderly are mostly chronic patients who require frequent check-ups of multiple vital signs, some of which (e.g., blood pressure and blood glucose) vary greatly according to the daily activities that the elderly are involved in. Therefore, the development of novel wearable intelligent systems to effectively monitor the vital signs continuously over a 24 hour period is in some cases crucial for understanding the progression of chronic symptoms in the elderly. In this paper, recent development of Wearable Intelligent Systems for e-Health (WISEs) is reviewed, including breakthrough technologies and technical challenges that remain to be solved. A novel application of wearable technologies for transient cardiovascular monitoring during water drinking is also reported. In particular, our latest results found that heart rate increased by 9 bpm (P < 0.001) and pulse transit time was reduced by 5 ms (P < 0.001), indicating a possible rise in blood pressure, during swallowing. In addition to monitoring physiological conditions during daily activities, it is anticipated that WISEs will have a number of other potentially viable applications, including the real-time risk prediction of sudden cardiovascular events and deaths.