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Effects of air-impingement jet drying on drying kinetics and quality retention of tomato slices
Si Tan,Yiwen Miao,Hongxia Xiang,Weihua Tan,Wenfeng Li 한국식품과학회 2021 Food Science and Biotechnology Vol.30 No.5
The purpose was to explore the drying kinetics,the moisture effective diffusivities, color, total polyphenols,lycopene and antioxidant activities of dried tomatoslices by air-impingement jet drying (AIJD). The resultsshowed that high temperature increased the drying rate, andModified Page model accurately predicted the AIJD characteristicsof tomato slices. AIJD is better than hot airdrying in shortening drying time, enhancing drying rate anddecreasing the loss of total polyphenols, lycopene andantioxidant capacity of tomato slices. Tomato slices driedby AIJD also showed higher lightness and redness. Lycopenecontent and antioxidant activity of tomato slices driedby AIJD were increased by higher drying temperature. Based on experimental data, AIJD at 80 C can be used intomato drying process due to the advantages in dryingefficiency and content of bioactive compounds. This studywill provide helpful information for the production of highquality of dried tomato products.
Tan, Xiaojun,Wang, Weihua,Li, Ping Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.9
The reaction mechanism between azacyclopropenylidene and epoxypropane has been systematically investigated employing the second-order M${\o}$ller-Plesset perturbation theory (MP2) method to better understand the reactivity of azacyclopropenylidene with four-membered ring compound epoxypropane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. It was found that for the first step of this reaction, azacyclopropenylidene can insert into epoxypropane at its C-O or C-C bond to form spiro intermediate IM. It is easier for the azacyclopropenylidene to insert into the C-O bond than the C-C bond. Through the ring-opened step at the C-C bond of azacyclopropenylidene fragment, IM can transfer to product P1, which is named as pathway (1). On the other hand, through the H-transferred step and subsequent ring-opened step at the C-N bond of azacyclopropenylidene fragment, IM can convert to product P2, which is named as pathway (2). From the thermodynamics viewpoint, the P2 characterized by an allene is the dominating product. From the kinetic viewpoint, the pathway (1) of formation to P1 is primary.
Tan, Xiaojun,Li, Zhen,Sun, Qiao,Li, Ping,Wang, Weihua Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.6
The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+$G^*$ level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+$G^*$ single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly $via$ a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed $via$ TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).
Tan, Xiaojun,Wang, Weihua,Li, Ping,Li, Qingyan,Cheng, Lei,Wang, Shufen,Cai, Weiwang,Xing, Jinping Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.5
The geometries and isomerization of the alkylidene silylenoid $H_2C$ = SiLiF as well as its insertion reactions with R-H (R = F, OH, $NH_2$) have been systematically investigated at the B3LYP/6-311+$G^*$ level of theory. The potential barriers of the three insertion reactions are 97.5, 103.3, and 126.1 kJ/mol, respectively. Here, all the mechanisms of the three reactions are identical to each other, i.e., an intermediate has been formed first during the insertion reaction. Then, the intermediate could dissociate into the substituted silylene ($H_2C$ = SiHR) and LiF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies for the three reactions are -36.4, -24.3, and 3.7 kJ/mol, respectively. Compared with the insertion reaction of $H_2C$ = Si: and R-H (R = F, OH and $NH_2$), the introduction of LiF makes the insertion reaction occur more easily. Furthermore, the effects of halogen (F, Cl, Br) substitution and inorganic salts employed on the reaction activity have also been discussed. As a result, the relative reactivity among the three insertion reactions should be as follows: H-F > H-OH > H-$NH_2$.
Xiaojun Tan,Zhen Li,Qiao Sun,Ping Li,Weihua Wang 대한화학회 2012 Bulletin of the Korean Chemical Society Vol.33 No.6
The reaction mechanism between cyclopropenylidene and formaldehyde has been systematically investigated employing the MP2/6-311+G* level of theory to better understand the cyclopropenylidene reactivity with carbonyl compound. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. Energies of all the species are further corrected by the CCSD(T)/6-311+G* single-point calculations. It was found that one important reaction intermediate (INTa) has been located firstly via a transition state (TSa). After that, the common intermediate (INTb) for the two pathways (1) and (2) has been formed via TSb. At last, two different products possessing three- and four-membered ring characters have been obtained through two possible reaction pathways. In the reaction pathway (1), a three-membered ring alkyne compound has been obtained. As for the reaction pathway (2), it is the formation of the four-membered ring conjugated diene compound. The energy barrier of the ratedetermining step of pathway (1) is lower than that of the pathway (2), and the ultima product of pathway (2) is more stable than that of the pathway (1).
Xiaojun Tan,Weihua Wang,Ping Li 대한화학회 2014 Bulletin of the Korean Chemical Society Vol.35 No.9
The reaction mechanism between azacyclopropenylidene and epoxypropane has been systematically investigated employing the second-order Møller-Plesset perturbation theory (MP2) method to better understand the reactivity of azacyclopropenylidene with four-membered ring compound epoxypropane. Geometry optimization, vibrational analysis, and energy property for the involved stationary points on the potential energy surface have been calculated. It was found that for the first step of this reaction, azacyclopropenylidene can insert into epoxypropane at its C-O or C-C bond to form spiro intermediate IM. It is easier for the azacyclopropenylidene to insert into the C-O bond than the C-C bond. Through the ring-opened step at the C-C bond of azacyclopropenylidene fragment, IM can transfer to product P1, which is named as pathway (1). On the other hand, through the H-transferred step and subsequent ring-opened step at the C-N bond of azacyclopropenylidene fragment, IM can convert to product P2, which is named as pathway (2). From the thermodynamics viewpoint, the P2 characterized by an allene is the dominating product. From the kinetic viewpoint, the pathway (1) of formation to P1 is primary.
Xiaojun Tan,Weihua Wang,Ping Li,Qingyan Li,Lei Cheng,Shufen Wang,Weiwang Cai,Jinping Xing 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.5
The geometries and isomerization of the alkylidene silylenoid H2C = SiLiF as well as its insertion reactions with R-H (R = F, OH, NH2) have been systematically investigated at the B3LYP/6-311+G* level of theory. The potential barriers of the three insertion reactions are 97.5, 103.3, and 126.1 kJ/mol, respectively. Here, all the mechanisms of the three reactions are identical to each other, i.e., an intermediate has been formed first during the insertion reaction. Then, the intermediate could dissociate into the substituted silylene (H2C = SiHR) and LiF with a barrier corresponding to their respective dissociation energies. Correspondingly, the reaction energies for the three reactions are ‒36.4, ‒24.3, and 3.7kJ/mol, respectively. Compared with the insertion reaction of H2C = Si: and R-H (R = F, OH and NH2), the introduction of LiF makes the insertion reaction occur more easily. Furthermore, the effects of halogen (F, Cl, Br) substitution and inorganic salts employed on the reaction activity have also been discussed. As a result, the relative reactivity among the three insertion reactions should be as follows: H-F > H-OH > H-NH2.
Huixia Zhu,Shiru Jia,Hongjiang Yang,Weihua Tang,Zhilei Tan,Yuanyuan Jia 한국식품과학회 2010 Food Science and Biotechnology Vol.19 No.6
The feasibility of a novel bacteriostatic sausage casing made of bacterial cellulose (BC) embedded with ε-polylysine (ε-PL) was evaluated. The ε-PL/BC composite was prepared by immersing BC tubes in ε-PL solution and its characteristics were analyzed with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD),and atomic force microscopy (AFM) techniques, respectively. The results suggested that ε-PL molecules were incorporated into the cellulose fiber networks and the ε-PL/BC composite might have a novel unique structure. No significant loss of antimicrobial activity was observed even after autoclaving at 121℃ for 30 min and the oxygen permeability was far below than that of polyethylene (PE) and polyvinyl alcohol (PVA) membrane. Its tensile strength was 51.8 MPa. The ε-PL/BC composite exhibits bacteriostatic and/or bacteriocidal activities against a broad spectrum of Gram-positive and Gram-negative bacteria; as a result, an extended shelf life than controls was observed for sausage packaged with the ε-PL/BC composite.
A reduced time-varying model for a long beam on elastic foundation under moving loads
Guiming Mei,Caijin Yang,Shulin Liang,Jiangwen Wang,Dong Zou,Weihua Zhang,Yunshi Zhao,Zhong Huang,Shuqi Song,Mengying Tan,Yao Cheng,Bingrong Miao 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.9
Dynamics of a long beam on the elastic foundation subjected to moving loads is studied in the present paper. The sliding window technique is used to dynamically truncate the long beam and a reduced time-varying beam system is obtained. The Hamilton’s principle is employed to establish the equations of motion of the reduced system. The variable separation method is adopted to solve dynamical responses of the reduced system. Examples of a long simply supported Timoshenko beam on the nonlinear foundation subjected to a single moving load and multiple loads are included. Numerical results of the reduced model compared with the ones obtained from the moving element model adapted in literature are carried out to show the validity and the good efficiency of the method proposed in the present paper.