Northeast Forestry University , located in Harbin, Heilongjiang Province, is an institution of higher education and research under jurisdiction of the Ministry of Education of the People's Republic of China, serve as the largest forestry university in China and a key university within the scope of national "211 Project". Wikipedia.
Ding Y.,Northeast Forestry University
Nonlinear Dynamics | Year: 2017
In this paper, we study the mathematical model about variable frequency water supply system in the process of applying glue to particleboard. Based on the original linear ordinary differential model, the effects of time delay and the nonlinear factor are considered. Then, we obtain the delayed nonlinear differential equation associated with variable frequency water supply system. Further, we consider the existence and stability of the equilibria and the existence of several types of bifurcations in this functional differential equation. Next, we derive the normal forms of Hopf bifurcation and Bogdanov–Takens bifurcation by using the multiple time scales method and the center manifold reduction method, respectively, and analyze the classifications of local dynamics. Finally, by using Matlab software, we obtain numerical simulations with estimated values of parameters and show the existence of stable equilibrium, stable periodic-1, periodic-2, and periodic-4 solutions, and a complex chaotic attractor from a sequence of period-doubling bifurcations. © 2017 Springer Science+Business Media B.V.
Liu T.,Northeast Forestry University |
Li Q.,Northeast Forestry University |
Li Q.,Zhejiang University of Technology
Journal of Drug Targeting | Year: 2014
Organic anion-transporting polypeptides (OATPs) encoded by the SLCO genes constitute an important transporter superfamily that mediates transmembrane transport of various clinical drugs and endogenous nutrients. Eleven human OATPs with different transport functions are expressed in various tissues. Bile acids, steroid hormone conjugates, prostaglandins, testosterone and thyroid hormones that promote cell proliferation are typical substrates of OATPs. Many important clinical drugs have been identified as substrates of OATP1B1, OATP1B3, OATP2B1 and OATP1A2. Liver-specific OATP1B1 and OATP1B3 as well as testis-specific OATP6A1 are expressed in malignancies and can act as biomarkers for many tumours. Various studies have shown the associations of genetic polymorphisms in OATP genes with the uptake pharmacokinetics of their substrates. Because of their abundant expression in tumours and their high transport activity for many cancer drugs, OATPs should be considered as important therapeutic targets in anti-cancer drug design. © 2014 Informa UK Ltd.
Ren X.,Northeast Forestry University |
Chen L.,Northeast Forestry University
Biosensors and Bioelectronics | Year: 2014
A newly designed molecularly imprinted polymer (MIP) material was fabricated and successfully utilized as recognition element to develop a quantum dots (QDs) based MIP-coated composite for selective recognition of the template cyphenothrin. The MIP-coated QDs were characterized by fluorescence spectrophotometer, Fourier transform infrared spectroscopy, transmission electron microscope, dynamic light scattering and X-ray powder diffraction. The fluorescence of the coated QDs is quenched on loading the MIP with cyphenothrin, and the effect is much stronger for the MIP than for the non-imprinted polymer, which indicates the MIP could as a recognition template composite. This method can detect down to 9.0nmolL-1 of cyphenothrin in water, and a linear relationship has been obtained covering the concentration range of 0.1-80.0μmolL-1. The method has been used in the determination of cyphenothrin in water samples and gave recoveries in the range from 88.5% to 97.1% with relative standard deviations in the range of 3.1-6.2%. The present study provides a new and general strategy to fabricate inorganic-organic MIP-coated QDs with highly selective recognition ability in aqueous media and is desirable for chemical probe application. © 2014 Elsevier B.V.
Zu Y.,Northeast Forestry University
International journal of nanomedicine | Year: 2011
Oligomycin-A (Oli-A), an anticancer drug, was loaded to the folate (FA)-conjugated chitosan as a tumor-targeted drug delivery system for the purpose of overcoming the nonspecific targeting characteristics and the hydrophobicity of the compound. The two-level factorial design (2-LFD) was applied to modeling the preparation process, which was composed of five independent variables, namely FA-conjugated chitosan (FA-CS) concentration, Oli-A concentration, sodium tripolyphosphate (TPP) concentration, the mass ratio of FA-CS to TPP, and crosslinking time. The mean particle size (MPS) and the drug loading rate (DLR) of the resulting Oli-loaded FA-CS nanoparticles (FA-Oli-CSNPs) were used as response variables. The interactive effects of the five independent variables on the response variables were studied. The characteristics of the nanoparticles, such as amount of FA conjugation, drug entrapment rate (DER), DLR, surface morphology, and release kinetics properties in vitro were investigated. The FA-Oli-CSNPs with MPS of 182.6 nm, DER of 17.3%, DLR of 58.5%, and zeta potential (ZP) of 24.6 mV were obtained under optimum conditions. The amount of FA conjugation was 45.9 mg/g chitosan. The FA-Oli-CSNPs showed sustained-release characteristics for 576 hours in vitro. The results indicated that FA-Oli-CSNPs obtained as a targeted drug delivery system could be effective in the therapy of leukemia in the future.
Li Q.,Northeast Forestry University
International journal of nanomedicine | Year: 2011
The purpose of this study was to develop a method for targeted delivery of 10-hydroxycamptothecin (HCPT)-loaded nanoparticles (NPs) to cancer cells. We first used a supercritical antisolvent process to prepare micronized HCPT (nHCPT), and then folate-conjugated human serum albumin (HSA) nHCPT-loaded NPs (FA-HSA-nHCPT-NPs) were prepared using a NP-coated method combined with a desolvation technique. The amount of folate conjugation was 16 μg · mg(-1) HSA. The particle size of the spherical nHCPT microparticles obtained was 118.5 ± 6.6 nm. The particle size and zeta potential of the FA-HSA-nHCPT-NPs were 233.9 ± 1.2 nm and -25.23 ± 2.98 mV, respectively. The FA-HSA-nHCPT-NPs exhibited a smooth surface and a distinct spherical shape, and the results of differential scanning calorimetry and X-ray diffraction indicated that the FA-HSA-nHCPT-NPs presented in a nanostructured amorphous state. The FA-HSA-nHCPT-NPs showed sustained-release characteristics for 120 hours in vitro, with a drug-loading content of 7.3% and an encapsulating efficiency of 79.1%. The FA-NPs were effective delivery systems for uptake by SGC7901 cells compared with folate-free NPs. These results suggest that a NP-coated method combined with a desolvation technique is effective for preparing NPs with drugs having poor solubility in water and most organic solvents, using albumin as the wall material. FA-HSA-NPs are a stable delivery system and have the potential for targeted delivery of anticancer drugs.
Chen L.,Northeast Forestry University |
Li B.,Northeast Forestry University
Food Chemistry | Year: 2013
A rapid and selective method was successfully developed using magnetic molecularly imprinted polymer (MMIP) as sorbent for the extraction of chloramphenicol from honey samples. The extraction process was carried out in a single step by blending and stirring the sample, extraction solvent and polymers. When the extraction was completed, the MMIPs adsorbing the analyte were separated from the sample matrix by an external magnet. The analyte eluted from the MMIPs by methanol under ultrasound assisted was analysed by liquid chromatography-tandem mass spectrometry. Various parameters affecting the extraction efficiency were evaluated for achieving optimal recovery and reducing non-specific interactions. Under optimal conditions, the detection limit of CAP was 0.047 ng g-1. The relative standard deviations of intra- and inter-day ranging from 4.1% to 5.3% and from 2.9% to 7.1% were obtained, respectively. The method was applied to determine CAP in six honey samples. The recoveries of CAP in these samples from 84.3% to 90.9% were obtained. © 2013 Elsevier Ltd. All rights reserved.
Zhou Q.-M.,Northeast Forestry University
Nonlinear Analysis: Real World Applications | Year: 2015
In the present paper, in view of the variational approach, we discuss the nonlinear eigenvalue problems for p(x)-Laplacian-like operators, originated from a capillary phenomenon. Under some suitable conditions, we prove the existence of nontrivial solutions of the system for every parameter λ>0. © 2014 Elsevier Ltd. All rights reserved.
Wang L.,Northeast Forestry University |
Li J.,Northeast Forestry University
Industrial Crops and Products | Year: 2013
Cellulose from flax shive was modified with quaternary ammonium groups to facilitate removal of C.I. Reactive Red 228 (RR228) dye from aqueous media. The adsorption of RR228 was investigated at various temperatures, adsorbent doses, initial dye concentrations and pH values. Two kinetic models were used to describe the adsorption process. Two isotherm models were applied to evaluate the adsorption equilibrium, and its thermodynamic parameters were calculated. The maximum capacity of the modified flax shive cellulose for adsorption of RR228 was 190mgg -1 at pH 3 under dose of 0.4gL -1 and initial concentration of 80mgL -1. The adsorption process and equilibrium of RR228 were well fitted by a pseudo-second-order kinetic model and Langmuir model, respectively. Thermodynamic evaluation indicated that the adsorption is exothermic, spontaneous, and favorable. © 2012 Elsevier B.V.
Northeast Forestry University | Date: 2015-01-16
The present invention disclosed N-acetyl amino acid ester derivatives of betulin and the preparation method thereof, the method comprising the steps that in the presence of an alkaline substance, a catalyst and a racemization-inhibitor, the carboxyl group of N-acetyl amino acid is activated by a coupling agent; and then the activated N-acetyl amino acid is reacted with betulin via esterification reaction to obtain the N-acetyl amino acid ester derivative of betulin. The present invention provided a simple synthesis method to synthesize the N-acetyl amino acid ester derivatives of betulin by using betulin as a precursor compound and modifying the molecular structure of betulin. Such structural modification of betulin significantly enhances the anti-tumor activity of the betulin derivatives and therefore has important values.
Northeast Forestry University | Date: 2012-06-15
Provided is a 10-methoxycamptothecine derivate of formula (1), wherein R is selected from hydrogen, C_(1-6 )alkyl, C_(1-6 )haloalkyl, aryl substituted C_(1-6 )alkyl, phosphate substituted C_(1-6 )alkyl, amino-substituted C_(1-6 )alkyl, carboxyl substituted C_(1-6 )alkyl, hydroxyl substituted C_(1-6 )alkyl, and amide- substituted C_(1-6 )alkyl; R_(1 )is selected from hydrogen and t-butoxycarbonyl substituted amino. Also provided in the present invention are the preparation method of the derivate and the use thereof in anti-tumor drug preparation.