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Lin L.,Key Laboratory of Tropical Crop Products Processing | Cheng S.,Key Laboratory of Tropical Crop Products Processing | Li J.,Key Laboratory of Tropical Crop Products Processing | Huang M.,Key Laboratory of Tropical Crop Products Processing | And 2 more authors.
Nongye Gongcheng Xuebao/Transactions of the Chinese Society of Agricultural Engineering | Year: 2013

Pesticides are widely used as an insurance policy against devastating crop losses from pests and diseases. Excessive usage of pesticides may lead to contamination of the crop and the environment, eventually posing a risk of pesticide-related illnesses to humans. Previous literature has shown that water washing is only partially effective in removing pesticides, and in the case of liposoluble pesticides, a cosolvent must be used as an adjuvant. Recently, naturally occurring adjuvants are gaining prominence over synthetic chemical compounds. Tea tree oil (TTO, the oil of Melaleuca alternifolia), a natural, volatile essential oil, is mainly extracted by steam distillation from the fresh leaves and terminal branchlets of the plant. It has attracted significant interest due to its antifungal, antiviral, and antibacterial bioactivities. However, to the best of our knowledge, there are fewer experimental data evaluating its efficacy in the removal of pesticide residues. In this study, the effects of TTO on removing pesticide residue were carried out in the cowpea. Volume: volume (v: v) concentrations of 0.05%, 0.1%, 0.2%, 0.4% and 0.8% of TTO and water soluble tea tree oil (WTTO) in water were used to remove a standardized pesticide mixture (organophosphorus, pyrethroid, and carbamate compounds) from cowpeas. Sample pretreatment (pesticide application to cowpeas) was performed according to agricultural industry standards. The objective pesticide residues in cowpeas were assayed by gas chromatography (GC) and chromatography-mass spectrometry detection (GC-MS), and then the clearance rate was calculated. The results showed that TTO was able to remove the three kinds of pesticides from cowpeas. Moreover, the removal efficiency increased with increasing concentration of TTO. The effect of clearing organophosphate was much more obvious than that of either pyrethroid or carbamate. It was suggested that small liposoluble molecules of TTO rapidly infiltrate the cowpea surface to dissolve the organophosphate pesticides depending on the compatibility principle. For carbamate pesticides, such as carbofuran, owing to its high polarity, TTO could not infiltrate into the internal of cowpeas to dissolve the residuals, resulting in the lower clearing efficiency. In conclusion, to remove pesticide residues, the commercially available extract TTO was more effective than deionized water in removing pesticide residues from fruits and vegetables. In comparison, WTTO was even more effective in removing pesticide residues than the same concentration of TTO. Among all treatments, 0.8% WTTO showed the greatest removal efficiency. The removal rates achieved by WTTO were as follows: 80.48% for isocarbophos, 94.54% for malathion, 82.79% for triazophos, 84.58% for chlorpyrifos, 72.20% for omethoate, 80.51% for cypermethrin, and 72.21% for meta-tolyl-N-methylcarbamate (MTMC). Therefore, TTO is expected to be useful as a fruit and vegetable cleaning adjuvant.


Li J.-H.,Chinese Academy of Sciences | Li J.-H.,Key Laboratory of Tropical Crop Products Processing | Li J.-H.,State Important Engineering and Technology Research Center for Key Tropical Crops | Huang M.-F.,Chinese Academy of Sciences | And 6 more authors.
Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis | Year: 2010

In the present paper, soluble Ca content in banana pulp was analyzed with pretreatment of digestion model in vitro. All the samples were digested by strong acid (perchloric acid and nitric acid with 1:4 ratio) and determined by AA700 flame atomic absorption spectrophotometry (FAAS). Meanwhile, the reproducibility of the analytical method was investigated. The results showed that (1) Content of Ca was 1.479 mg·g-1·DW in eighty percent maturity banana pulp. And the relative standard deviation was 4.12%. (2) Contents of Ca in the soluble and insoluble fractions were 1.108 and 0.412 mg·g-1·DW, respectively in eighty percent maturity banana pulp with pretreatment of digestion model in vitro. The extraction rate was 74.9% and the residue rate was 27.8%. (3) The relative standard deviations of the analytical results of Ca contents in those two fractions were 2.56% and 9.10%, respectively, in the reproducibility tests. It was showed that the digestion model in vitro did not affect the reproduction quality significantly. Moreover, the deviation between the theoretical value and the summation value of the extraction and the residue rates was only 2.7%, which showed good availability of the digestion model in vitro to be used as a pretreatment method in mineral element analysis process. (4) Relative standard deviation and recovery yield in the determination procedure were 0.11%(n=9)and 99.2%, respectively.


Chen J.,Zhanjiang Normal University | Xu K.,Key Laboratory of Tropical Crop Products Processing | Pan R.,Zhanjiang Normal University | Peng Z.,Key Laboratory of Tropical Crop Products Processing | Ma L.,Zhanjiang Normal University
Polymer Composites | Year: 2014

The purpose of this work is to study the reinforcement effect of modified coal gangue (CG) on natural rubber (NR); carbon black (CB) was taken as reference filler. The addition of CG and CB to NR with the total filler loading fixed at 35 phr. The orthogonal experiment was employed to reveal the modification conditions on reinforcing properties. The results show that modification conditions such as weight ratio of coupling agent (CA), calcining temperature (CT), and calcining time (CM) affect the strengthening properties of CG, and CA is the most important factor influencing the tensile strength of NR, the order of influence can be expressed as CA > CT > CM. The optimum modification conditions are CT 800°C, CM 1 hr, and CA 2%. 300% modulus of NR composites filled with modified CG (17.5 phr)/CB (17.5phr) hybrid filler is similar to NR filled with CB alone at same filler loading, while elongation at break increases significantly for existent of CG. The effect of heat treatment and modification conditions of CG were tested by particle size distribution, scanning electron microscopy, Fourier transform infrared spectra, and X-ray diffraction. The results show that the specific surface area of CG increased and hydroxyl group in crystal structure of CG removed under heat treatment. Dynamic mechanical analysis results show that the storage modulus and tan δ of CG filled NR composites are higher while Tg is less than that of CB, indicating the existence of a strong and stiff interface between filler and NR matrix. © 2014 Society of Plastics Engineers.


Chen S.,Chemistry and Chemical Engineering SchoolInstitute of Physical ChemistryLingnan Normal UniversityZhanjiang | Chen J.,Chemistry and Chemical Engineering SchoolInstitute of Physical ChemistryLingnan Normal UniversityZhanjiang | Xu K.,Key Laboratory of Tropical Crop Products Processing | Pan R.,Chemistry and Chemical Engineering SchoolInstitute of Physical ChemistryLingnan Normal UniversityZhanjiang | And 3 more authors.
Polymer Composites | Year: 2015

The objective of this study was to investigate three kinds of filler with completely different morphology on mechanical properties of natural rubber (NR). Coal gangue (CG) are derived from natural deposits are composed principally by illite and quartz. CG, carbon black (CB), and multiwalled carbon nanotube (CNT) were used as hybrid fillers in NR. CNTs were dispersed into NR latex by ultrasonic irradiation and then the mixed latex were coagulated to obtain the CNTs/NR masterbatch, then mechanical mixing method was employed to prepare the CG/CB/CNTs/NR composites. The addition of CG, CB, and CNTs to NR was varied with the total filler loading fixed at 35 phr. The mechanical properties of NR composites were studied in terms of tensile and dynamic mechanical analysis (DMA). The results showed that the tensile strength and modulus 300% (M300) of all hybrid samples were higher than the composites only loaded CG; and the highest tensile strength of NR loaded with hybrid fillers achieved at sample of loading amount of CG 17.5, CB 15.5, and CNTs 2 phr, whose M300 and elongation at break was obviously higher than that of only CB loaded NR composites; The inclusion CG improves the tensile strength of NR without the sacrifice of its extensibility, while CB and CNTs brings together the enhancement in the ultimate strength and the reduction in the extensibility. DMA results revealed that the existence of CG can improve the dispersion of CB and CNTs in NR matrix. © 2015 Society of Plastics Engineers.


Sun Y.,Hangzhou Normal University | Liu Y.,Zhejiang Academy of Agricultural Sciences | Li Y.,Key Laboratory of Tropical Crop Products Processing | Lv M.,Key Laboratory of Tropical Crop Products Processing | And 3 more authors.
Carbohydrate Polymers | Year: 2011

Antibacterial membranes were prepared from a mixture of hydrolyzed curdlan and chitosan. The elongation-at-break and water vapor transmission rate of curdlan/chitosan blended membranes were substantially improved when the temperature was high (90 °C) due to curdlan gel formation and the interaction between the hydroxyl groups of curdlan and the amino groups of chitosan. This was confirmed by Fourier transform infrared spectroscopy. The membranes were further investigated for their miscibility between the two components using differential scanning calorimetric measurements, dynamic mechanical analysis, optical microscopy, and scanning electron microscopy. High reaction temperatures (90 °C) and low curdlan contents caused better interactions between components, and allowed membranes to be prepared with higher storage moduli and lower water absorption rates. The 4 bacteria strains were chosen as target bacteria using the optical density method to prove the antibacterial activity of the membranes obtained. The resulting curdlan/chitosan membranes exhibited outstanding antibacterial activity. © 2010 Elsevier Ltd. All rights reserved.


Lin L.,Chinese Academy of Sciences | Huang X.,Chinese Academy of Sciences | Huang X.,University of Sichuan | Li J.,Chinese Academy of Sciences | And 3 more authors.
Advanced Materials Research | Year: 2013

A Box-Behnken experimental design and response surface methodology (RSM) was employed to optimize the parameters of ultrasonic extraction of phenolics from longan seed based on the single-factor experiments. The effects of extraction temperature, methanol concentration and extraction time on the extraction yield of phenolics from longan seed were investigated. The major parameter influencing the extraction was the extraction temperature. In this experiment, the maximal extraction yield of phenolics was obtained with 5.931 ± 0.016% (n = 3) at extraction temperature 82°C, methanol concentration 50% and extraction time 41 min. Under optimal conditions, the activity predicted by the model agreed well with experimental data. © (2013) Trans Tech Publications, Switzerland.


Shi X.,Key Laboratory of Tropical Crop Products Processing | Shi X.,Qingdao University of Science and Technology | Zhu Z.,Qingdao University of Science and Technology | Bi W.,Qingdao University of Science and Technology | Zhao S.,Qingdao University of Science and Technology
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2011

The damping properties of ethylene-vinyl acetate rubber (EVM)/ethylene-propylene rubber (EPDM) blends were investigated by dynamic mechanic analyzer (DMA), in which BIPB was chosen as the curing agent. The results show that EVM/EPDM blends with various ratios have two separated tanδ peaks with "valley" data, which can't improve the damping property of blend. Zinc diacrylate (Zn(AA)2) can enlarge the tanδ peak. EVM/EPDM have two separated damping peaks with "valley" data in between 20°C~40°C after the addition of EVM900 in blend which indicates that EVM900 cann't effectively improve the damping properties of blends. Polyvinylchloride (PVC) and EVM 700 are fully compatible so that PVC can obviously improve the damping property of EVM/EPDM blends in high temperature zone.


Shi X.,Qingdao University of Science and Technology | Shi X.,Key Laboratory of Tropical Crop Products Processing | Bi W.,Qingdao University of Science and Technology
Gaofenzi Cailiao Kexue Yu Gongcheng/Polymeric Materials Science and Engineering | Year: 2011

The damping properties of ethylene vinyl-acetate copolymer (EVM)/ethylene-propylene-diene monomer (EPDM) and EVM/nitrile butadiene rubber (NBR) blends, with di(tert-butylperoxyisopropyl)benzene (BIBP) as the curing agent, were investigated by dynamic mechanic analyzer (DMA). The effects of PVC, N-cyclohexyl-2-benzothiazole (CZ), and dicumyl peroxide (DCP) on the damping properties were studies. The results show that in EVM/EPDM/PVC blends, PVC and EVM700 are compatible with one tanδ peak, which improves the damping properties of EVM at higher temperature. In EVM/NBR blends, PVC and EVM/NBR blends are partially compatible with two combined tanδ peaks, which widens the effective damping temperature range to 62.4°C. 1.4 phr DCP enlargs the tanδ peak of EVM/NBR with the effective damping temperature range up to 64.9°C. Small amount of CZ can enlarge the tanδ peak of EVM/NBR. 5 phr Zn(AA)2 can also widen the tanδ peak of EVM/NBR.


Yongzhen L.,Key Laboratory of Rubber Plastics QUST | Yongzhen L.,Key Laboratory of Tropical Crop Products Processing | Jidong H.,Key Laboratory of Rubber Plastics QUST | Guozhen C.,Key Laboratory of Rubber Plastics QUST | And 2 more authors.
Journal of Applied Polymer Science | Year: 2010

Polymorpholine-2,5-dione-block-polylactide (PMD-b-PLA) was synthesized via two-step anionic ring-opening polymerization at room temperature. First step of ring-opening polymerization was the ring-opening of mor-pholine-2,5-dione (MD). It was carried out in an airtight and dry polymerization tube using potassium ethoxide/THF (0.2M/L) as an initiator for 90 min. Then lactide was ring-opened in THF solution by the potassium alcoholate of PMD. From the FTIR of the copolymer, we can find all the peaks in PLA and PMD. The 1H-NMR of copolymer gave us a proof to the principle of the anionic ring-opening polymerization and the fraction of PMD in the copolymer was calculated as 86.3%. DSC analysis of copolymer indicated that it was a copolymer with one T g (63.6°C) and two T ms (155.6 and 171.4°C) instead of a mixture of PMD and PLA. The yields of the PMD and the copolymer were 32 and 26%, respectively. © 2010 Wiley Periodicals, Inc.


Xu H.,East China University of Science and Technology | Xu H.,Key Laboratory of Tropical Crop Products Processing | Fang L.,Key Laboratory of Tropical Crop Products Processing | Wu C.,Key Laboratory of Tropical Crop Products Processing
Journal of Macromolecular Science, Part B: Physics | Year: 2011

To improve the dispersion stability of carbon black (CB) in an acrylic resin coating, a hindered phenolic antioxidant (AO80) was chosen to modify the CB by a solid state method based on the blending of CB and AO80 in an internal mixer. The modified CB (m-CB) was directly introduced into the acrylic resin with 50% solid content in butyl acetate by ball milling without any other treatment. That the majority of the m-CB particles were nanosized in ethanol was proven by a particle size analyzer. Transmission electron microscopy (TEM) and field emission scanning electron microscope (FESEM) micrographs indicated that the m-CB particles were also dispersed in the acrylic resin as nanoscale particles. Compared with the unmodified CB, the modification of CB can decrease the viscosity of the acrylic resin/m-CB nanocomposite and improve its flow property. The adhesion and gloss of the acrylic resin/m-CB nanocomposite were also improved. More importantly, the UV shielding and stability of the acrylic resin/m-CB nanocomposite were enhanced. © 2011 Copyright Taylor and Francis Group, LLC.

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