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Supra-micellar structures and reentrant effect of the assembled micelles can be observed in the self-assembly of polyelectrolyte copolymers in trivalent salt solution.

Recent outbreaks of coronavirus have brought serious challenges to public health around the world, and it is essential to find effective treatments. In this study, the 3C-like proteinase (3CLpro) of SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) has been considered as an important drug target because of its role in viral replication. We initially optimized 251 compounds at the PM7 level of theory for docking with 3CLpro, and then we selected the top 12 compounds for further optimization with the B3LYP-D3/6-311G** method and obtained the top four compounds by further molecular docking. Quantum chemistry calculations were performed to predict molecular properties, such as the electrostatic potential and some CDFT descriptors. We also performed molecular dynamics simulations and free energy calculations to determine the relative stability of the selected four potential compounds. We have identified key residues controlling the 3CLpro/ligand binding from per-residue based decomposition of the binding free energy. Convincingly, the comprehensive results support the conclusion that the compounds have the potential to become a candidate for anti-coronavirus treatment.

In order to improve the optoelectronic performance of π-conjugated molecules with electronic donors and electronic acceptors, people often choose multi-branch molecule structures, which can enhance the charge transfer ability.

The systemic toxicity and low efficacy of traditional chemotherapy for hepatocellular carcinoma (HCC) result in poor clinical outcomes. This study was designed to achieve targeted delivery of apoptin plasmid (AP) to liver tumors and killing of cancer cells using multifunctional nanoparticles (MFNPs) having sustained-release properties. The MFNPs featuring a distinct core-shell structure were prepared using poly(lactic-glycolic acid)-ε-polylysine copolymer and loaded with AP by adsorption. Specific targeting of liver tumor cells was achieved by biotinylation of the nanoparticles (NPs), while an improvement in lysosomal escape and nuclear localization enhanced the tumor cell killing capability of AP. Blank MFNPs exhibited good biocompatibility while AP-loaded NPs were found to exert strong inhibitory effects on both tumor cells in vitro and solid tumors in vivo. Taken together, these findings demonstrate a promising route for the development of tumor-targeted NPs which may lead to improved therapeutic strategies for treating HCC.

A comparative investigation on the photophysical properties of a quinoxaline derivative 4,4'-((1E,1'E)-quinoxaline-2,3-diylbis(ethene-2,1-diyl))bis(N,N-dimethylaniline) (QDMA2) was performed by employing many spectroscopies. Based on the pump-dump/push-probe measurement, it is found that a solvent-stabilized charge-transfer state can participate in the relaxation of excited QDMA2 with increasing solvent polarity. Meanwhile, the aggregated QDMA2 molecules were engineered into the organic light-emitting diode test, which showed a correlated color temperature value of 1875 K. With the help of a diamond anvil cell, the pressure-dependent photoluminescence of aggregated QDMA2 shows that the intermolecular interaction can affect the color and intensity of photoluminescence through adjusting the band gap and irradiative channel of the aggregated molecules. These results are important for understanding the structure-property relationships and the rational design of functional materials for optoelectronic applications.

Despite recent studies, relatively few are known about the diversity of fungal communities in the deep Atlantic Ocean. In this study, we investigated the diversity of fungal communities in 15 different deep-sea sediments from the South Atlantic Ocean with a culture-dependent approach followed by phylogenetic analysis of ITS sequences. A total of 29 fungal strains were isolated from the 15 deep-sea sediments. These strains belong to four fungal genera, including Aspergillus, Cladosporium, Penicillium, and Alternaria. Penicillium, accounting for 44.8% of the total fungal isolates, was a dominant genus. The antiaflatoxigenic activity of these deep-sea fungal isolates was studied. Surprisingly, most of the strains showed moderate to strong antiaflatoxigenic activity. Four isolates, belonging to species of Penicillium polonicum, Penicillium chrysogenum, Aspergillus versicolor, and Cladosporium cladosporioides, could completely inhibit not only the mycelial growth of Aspergillus parasiticus mutant strain NFRI-95, but also the aflatoxin production. To our knowledge, this is the first report to investigate the antiaflatoxigenic activity of culturable deep-sea fungi. Our results provide new insights into the community composition of fungi in the deep South Atlantic Ocean. The high proportion of strains that displayed antiaflatoxigenic activity demonstrates that deep-sea fungi from the Atlantic Ocean are valuable resources for mining bioactive compounds.

With the rapid growth of the aging population, abnormal detection has become a key issue in the medical and health field. Accurately detecting abnormal events in the monitoring video and giving feedback in real time can effectively reduce injuries even deaths caused by falls in the elderly. A novel Deepgait-based event detection method is proposed in this study for the elderly monitoring application. The classes of this problem contains abnormal behaviors, unusual events and normal daily life activities. To solve the above recognition problem, a novel deep convolutional features combined with joint Bayesian is proposed to model view variance. To evaluate the performance of the proposed model, two open behavioral data sets: Multiple cameras fall dataset and UR Fall Detection Dataset are adopted, where the mAP value of the improved Deepgait algorithm is 2.23% higher than that of Deepgait algorithm, and 5.4% higher than that of energy model (SSD) approach. The results suggest that our proposed monitoring system is an effective method for the elderly monitoring application.

Organic molecules with hybridized local and charge transfer (HLCT) characters have attracted attention because of their potential in the field of two-photon fluorescence imaging and light-emitting diodes (LEDs). Herein, the 4-(1,1-difluoro-1H-1λ4,10λ4-benzo[4,5]thiazolo[3,2-c][1,3,2]oxazaborinin-3-yl)-N,N-diphenylaniline (TOND) molecule is studied through various spectroscopy tests to explore the solvent-dependent photo-physical properties in the mono-disperse system and temperature-dependent photoluminescence behavior in the aggregation state system. The monodisperse TOND shows apparent two-photon fluorescence properties and its absorption section enhances with solvent polarity owing to the intramolecular charge transfer (ICT) process. The solvent-dependent relaxation process of excited TOND, which is affected by the ICT process, is analyzed by pump–probe and pump–dump–probe tests. The aggregated TOND can be fabricated into an LED, whose emission peak is centered at 566 nm with the Commission Internationale de l’Eclairage chromaticity (CIE) coordinates of (0.47, 0.51). Their radiative lifetime and photoluminescence quantum yield together decrease with increasing temperature, due to the activation of the non-radiative process at high temperatures. Our results provide a comprehensive insight into the optoelectronic properties of these organic molecules.

The pressure-dependent optoelectronic properties of all-inorganic perovskite CsPbBr3 nanocrystals (NCs) are investigated with steady-state and transient spectroscopy. The steady-state absorption an...

Quasi-2D perovskites have emerged as a promising luminescent material for perovskite light-emitting diodes (Pe-LEDs). However, efficiency and stability are still obstacles to practical application due to numerous defects and inefficient energy transfer of perovskite films. Herein, functional phenethylammonium bromine-modified CsPbBr

A Gram-negative, non-motile, non-spore-forming, aerobic and short rod-shaped bacterial strain R32T, was isolated from seawater of the South Atlantic Ocean. Strain R32T grew at 10–40 °C (optimum 28 °C), at pH 6.0–8.0 (optimum 7.0), and in the presence of 3–8 % NaCl (w/v) (optimum 5 %). Cells were oxidase- and catalase-positive. The 16S rRNA gene sequence of strain R32T shared the highest similarities with Mesonia oceanica (98.3 %), followed by Salegentibacter salarius (93.0 %), Salegentibacter mishustinae (92.8 %), Salegentibacter salegens (92.5 %) and Mesonia maritima (92.4 %). The dominant fatty acids were iso-C15 : 0 (32.7 %) and iso-C17 : 0 3-OH (21.1 %). Menaquinone-6 (MK-6) was detected as the sole respiratory quinone. The polar lipids found were phosphatidylethanolamine, three aminolipids and three unidentified lipids. The DNA G+C content was 35.0 mol%. The ANI value and dDDH value between strain R32T and the Salegentibacter and Mesonia species were 70.5–85.8 % and 18.7–30.5 %, respectively. Based on the results of the polyphasic characterization, strain R32T is considered to represent a novel species of the genus Mesonia , for which the name Mesonia hitae sp. nov. is proposed. The type strain is R32T (=MCCC 1A09780T=KCTC 72004T).

Chemotherapy has been the standard for cancer therapy, but the nonspecific cytotoxicity of chemotherapeutic agents and drug resistance of tumor cells has limited its efficacy. However, multidrug combination therapy and targeting therapy have resulted in enhanced anticancer effects and have become increasingly important strategies in clinical applications. In this study, a biotin-/lactobionic acid–modified poly(ethylene glycol)-poly(lactic-co-glycolic acid)-poly(ethylene glycol) (BLPP) copolymer was synthesized, and curcumin- and 5-fluorouracil-loaded nanoparticles (BLPPNPs/C + F) were prepared to enhance the treatment of hepatocellular carcinoma. Blank BLPPNPs were shown to have great biocompatibility via both in vitro and in vivo studies. Good targeting of tumor cells of BLPPNPs was confirmed by flow cytometry, fluorescence microscopy, and biodistribution. The synergistic anticancer effects of BLPPNPs/C + F were demonstrated by cytotoxicity and animal studies, while western blotting was used to further verify the synergistic effect of curcumin and 5-fluorouracil. The dual-targeting and drug-loaded codelivery nanosystem demonstrated higher cellular uptake and stronger cytotoxicity for tumor cells. Therefore, these dual-targeting NPs are a promising codelivery carrier that could be made available for cellular targeting of anticancer drugs to achieve better intracellular delivery and synergistic anticancer efficacy.

A comparative investigation on the photophysical properties of a quinoxaline derivative 4,4'-((1

Integration of multiple advantages in one system has been leveraged to overcome multiple biological barriers in anti-tumor therapeutic strategies. In this study, multi-functional nanoparticles (MFNPs) are constructed by layer-by-layer method. MFNPs are modified with pH-responsive elastic PEG-GPC3MAb (glypican-3 monoclonal antibody), which draws back into PEG layer in blood and normal tissues; and stretches out of MFNPs surface in the acidic tumor microenvironment. It is proved that blank MFNPs have good biocompatibility by MTT and acute toxicity assays. Elastic PEG chains are able to respond sensitively in different pH environments (6.8 and 7.4), which is demonstrated by transmission electron microscope (TEM) and

The photophysical properties of a donor-acceptor compound based on triphenylamine-modified vinylbenzothiazole derivative (BTTM) are investigated by multispectral techniques. Based on the pump-probe and pump-dump/push-probe technique, it is found that the hybridized localized excited (LE) and charge transfer (CT) state (HLCT) participates in the relaxation process of excited BTTM. The excited state is the LE-dominated HLCT state in cyclohexane; then it evolves to the CT-dominated HLCT state in a high polarity solvent. Meanwhile, a new intermediate state named the HLCT' state also exists in a high polar solvent. When the temperature of BTTM film drops, the increasing photoluminescence (PL) lifetime and PL quantum yield are assigned to the nonradiative recombination inactivation. The pump-probe data show that exciton-exciton annihilation originating from exciton collision gradually increases owing to the weakening of phonon-exciton scattering at low temperature. Our results provide comprehensive insight into the optoelectronic properties of organic molecules.

The deep-sea bacterium strain FA13 was isolated from the sediment of the South Atlantic Ocean and identified as Bacillus circulans based on 16S ribosomal DNA sequence. Through liquid fermentation with five media, the cell-free supernatant fermented with ISP2 showed the highest inhibition activities against mycelial growth of Aspergillus parasiticus mutant strain NFRI-95 and accumulation of norsolorinic acid, a precursor for aflatoxin production. Based on ISP2, uniform design was used to optimize medium formula and fermentation conditions. After optimization, the inhibition efficacy of the 20-time diluted supernatant against A. parasiticus NFRI-95 mycelial growth and aflatoxin production was increased from 0–23.1% to 100%. Moreover, compared to the original protocol, medium cost and fermentation temperature were significantly reduced, and dependence on seawater was completely relieved, thus preventing the fermentor from corrosion. This is the first report of a deep-sea microorganism which can inhibit A. parasiticus NFRI-95 mycelial growth and aflatoxin production.

Boron carbon oxynitride quantum dots (BCNO QDs) with blue emission were prepared via the template of SBA–15 (a typical mesoporous silica). A modulated photoluminescence sensor was developed based on the different quenching effects of Cu2+ or Hg2+ ions on the luminescence intensity of BCNO QDs. The Cu2+ or Hg2+ ions have an interaction with BCNO QDs due to the electrons transfer between the BCNO and Cu2+ or Hg2+ ions, and the detection limit of Cu2+ or Hg2+ ion concentration can be as less as 10 nM. The BCNO–Cr6+ mixture can be served as a turn–on fluorescent sensor for detecting the ascorbic acid based on the inner filter effect since overlapping of excitation and emission spectra between Cr6+ ions and BCNO QDs. Moreover, the BCNO QDs can also be applied to fingerprint identification and organic fluorescent films under ultraviolet excitation.

ACE inhibitory dipeptides from Xerocomus badius fermented shrimp processing waste were isolated with ethanol, macroporous resin, chloroform, and Sephadex G-10 in sequence and identified by LC-MS/MS system coupled with electrospray ionization source. Molecular docking was performed for exploring the mechanism of their inhibitions. The results showed that the identified ACE inhibitory dipeptides were Cys-Cys and Cys-Arg with IC50 values of 4.37 ± 0.07 and 475.95 ± 0.11 μM, respectively. The difference between ACE inhibitor potency of Cys-Cys and Cys-Arg could be explained by results of molecular docking. Cys-Cys formed crucial coordination between carboxyl oxygen and Zn(II), hydrogen bonds with residues Ala354(O), Ala356(HN), and Tyr523(OH), and a bump with the residue His387(NE2) at the active site of ACE. There was no coordination, except for 5 hydrogen bonds (at residues His353, Ala354, Glu384, Glu403, and Arg522) and a bump (Glu411) between Cys-Arg and active site of ACE. These findings highlighted that Cys-Cys could be considered as a novel potent ACE inhibitor, and coordination between its carboxyl oxygen and Zn(II) played significant role in defining its ACE inhibitor potency.

Chromium is one of main pollution in sea water, and the establishment of detecting kit is the research hot topic. In this study, immunized mice were obtained by immunogen Cr3+-EDTA-BSA, and hybridoma strains that secrete Cr3+-EDTA monoclonal antibody were selected. Cr3+-EDTA mAb were prepared with in vivo method. Then, Cr-kit for measurement of chromium was developed, and its application was executed in sea water and seafood. Two hybridoma strains of A321 and A424 were screened. The Cr-kit standard curve of the linear range was 1.0—512 μg/L, and limit of detection was 1.0 μg/L. The average recovery rates Cr spiked in samples of sea water, clam and shrimp were 102.62%, 94.69% and 96.29%, which were accordance with the results of ICP-AES. Totally, Cr-kit was successfully developed and behaved broad application potential in sea water and seafood.

A liquid fermentation process to bioconvert shrimp by-products was developed with two species of fungi, Boletus edulis and Suillus bovinus. Angiotensin I-converting enzyme (ACE) inhibitory, antioxidant activities of bioconverted products and the deodorization effect of fungal bioconversion were determined. Two species of fungi could grow quickly in shrimp by-products medium and deodorize shrimp by-products. Bioconverted products had higher ACE inhibitory and antioxidant activities than control medium. Water extracts without crude polysaccharides from mycelia of B. edulis had the highest ACE inhibitory activity (IC50 = 0.084 ± 0.011 mg/mL). Crude exopolysaccharides of B. edulis had higher antioxidant activity. Bioconversion with the fungus was proven to be a novel, practicable way to recycle shrimp by-products.

Thirty-six strains of marine actinomycetes were isolated from a sample of marine sediment collected from the Yellow Sea and evaluated in terms of their inhibitory activity on the growth of Aspergillus parasiticus and the production of norsolorinic acid using dual culture plate assay and agar diffusion methods. Among them, three strains showed strong antifungal activity and were subsequently identified as Streptomyces sp. by 16S rRNA gene sequencing analysis. The supernatant from the fermentation of the MA01 strain was extracted sequentially with chloroform and ethyl acetate, and the activities of the extracts were determined by tip culture assay. The assay results show that both extracts inhibited mycelium growth and toxin production, and the inhibitory activities of the extracts increased as their concentrations increased. The results of this study suggest that marine actinomycetes are biologically important for the control of mycotoxins, and that these bacteria could be used as novel biopesticides against mycotoxins.

Molecular biology is the frontier of life science and an important basic theoretical course. It is abstract and complex, and develops rapidly. In order to improve the teaching quality of molecular biology, the project team reformed the traditional single teaching mode, integrated and applied four teaching modes ie. LBL, PBL, CBL and RBL in the teaching of molecular biology, gave full play to the advantages of various teaching modes, and constructed a teacher-led-student-oriented teaching system. In this paper, its implementation process is introduced in detail to provide reference for the teaching of other biology courses.

To optimize the production conditions for exopolysaccharides with higher antioxidant activities fromXerocomus badiuscultured in shrimp byproduct medium, Plackett-Burman design, path of steepest ascent, and response surface methodology were explored. Based on the results of Plackett-Burman design and path of steepest ascent, a Box-Behnken design was applied to optimization and the regression models. The optimal cultural condition for high yield and antioxidant activity of the exopolysaccharides was determined to be 10.347% of solid-to-liquid ratio, a 4.322% content of bran powder, and a 1.217% concentration of glacial acetic acid. Culturing with the optimal cultural conditions resulted in an exopolysaccharides yield of4.588±0.346 g/L and a total antioxidant activity of2.956±0.105 U/mg. These values are consistent with the values predicted by the corresponding regression models (RSD < 5%).

Objectives Quercetin was applied as a model drug to evaluate the potential application of amphiphilic polylactic acid-hyperbranched polyglycerol (HPG-PLA) nanoparticles as carriers for poorly water-soluble drugs. Methods The drug delivery systems were characterized by dynamic light scattering, powder X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) and so forth. Key findings The results showed the particle sizes ranged from 205.3 to 433.3 nm with low polydispersity index. XRD and FTIR demonstrated that the crystal of the drug was converted to an amorphous state in the matrices and formed intermolecular interaction with carriers. The drug encapsulation efficiency and drug loading could reach 91.8% and 21.0%, respectively. Cell viability assay suggested the nanoparticles had good cytocompatibility. The in-vitro drug release profiles showed a sustained quercetin release up to 192 h, indicating the suitability of nanoparticles in sustained drug release. Furthermore, the influence of many factors on release profiles could also be evaluated for the potential of using nanoparticles as controlled release systems. Conclusions This system may be of clinical importance in both stabilizing and delivering hydrophobic drugs for the treatment of many diseases.

We prepared a β-CD functionalized hyperbranched polyglycerol (HPG) with the purpose of enhancing the nasal transport of insulin in rats. Insulin-loaded HPG-g-CD nanoparticles (NPs) were prepared and the size of the NPs ranged from 198 to 340 nm with a positive charge. The NPs exhibited a great capacity of associating insulin, reaching the efficiency as high as 88.21%. In vitro release showed that the release rate of insulin was much faster under acidic condition than physiological condition. In vitro cytotoxicity against Caco-2 cells showed that HPG-g-CDs had good biocompatibility. The in vivo evaluation in rats demonstrated that insulin-loaded HPG-g-CD NPs had the ability to significantly decrease the blood glucose concentrations. Furthermore, the capability of HPG-g-CD NPs to cross the nasal mucosal epithelia was proved by confocal laser scanning microscopy (CLSM). Consequently, the results suggest that the HPG-g-CD NPs are promising carriers for nasal insulin delivery.

Nanoparticles based on an amphiphilic copolymer with polylactic acid (PLA) grafted onto hyperbranched polyglycerol (HPG) were prepared by the use of BSA as a model protein. The characteristics of the nanoparticles were evaluated using particle size analyzer, transmission electron microscopy, and X-ray photoelectron spectroscopy. The secondary structure of BSA released from nanoparticles were analysed by circular dichroism experiments. Cell viability of nanoparticles was also evaluated by using NIH 3T3 cells. The mechanism of BSA release was studied by fitting experimental data to three model equations. Results indicated that BSA diffusion and the polymeric relaxation jointly governed the overall release process. The detailed analysis of BSA release was performed using the first-order kinetic model equation, which gave a good fit to the experimental release data. The influence of different copolymer structures and BSA loading capacities on release profiles were also evaluated for the potential of using nanoparticles as controlled release protein delivery systems.

Amphiphilic copolymers with polylactic acid (PLA) chains grafted onto hyperbranched polyglycerol (HPG) have been synthesized and characterized. The copolymer nanoparticles with corona and core structure were formed by self-assembly in aqueous solution. The loading capacity and association efficiency were up to 23% and 86%, respectively. Protein release profiles with different copolymer compositions and BSA concentrations all showed a burst effect followed by a continuous release phase. The released BSA from the copolymer nanoparticles remained in its original structure over a period of 4 days, as testified by circular dichroism spectroscopy. Furthermore, cell viability research suggested good biocompatibility of the copolymer nanoparticles, which have a promising potential for protein delivery system.

The objective of this work was to investigate the possibility of chitosan bearing β-cyclodextrin (CDen-g-CS) nanocomplexes for controlled protein release. CDen-g-CS was synthesized by a one-step procedure with N-succinylated chitosan and mono(6-(2-aminoethyl)amino-6-deoxy)-β-cyclodextrin in the presence of the water-soluble carbodiimide. The amount of β-CD grafted was up to 62.1 wt%. In vitro cytotoxicity against NIH 3T3 cells showed that CDen-g-CS was not cytotoxic and no significant difference of cytotoxicity was found between CDen-g-CS groups. Self-assembled nanocomplexes between CDen-g-CS and insulin were in the size range of 190–328 nm, with positive electrical charge (+3.7 to +25.5 mV) and high loading efficiency (37.7%). Insulin release in vitro was affected by the medium pH and the composition of copolymer. These results demonstrated that CDen-g-CS copolymer was a new promising vehicle for controlled protein release.

Estimation of physical properties of rock is essential to design rock structures and to evaluate the stability of rock slopes. It is well known that rock properties often vary from site to site, and even from specimen to specimen. So, in many cases, it requires many rock samples, much effort and cost to obtain the reliable data. In this study, an efficient testing method with small rock specimens was proposed and examined. At first, the preparation process for a cylindrical specimen, 10mm in diameter and 20mm in length, was developed. In the experimental work, the transparent triaxial vessel, developed by Okubo et al., was modified and used for the small specimen. Triaxial compression tests with constant loading rate were conducted with small specimens of Tage tuff, and it was found that cohesion, C, and angle of internal friction, φ, can be precisely obtained. By this test, the loading rate dependency of a stress-strain curve can be also obtained by just one small specimen with the loading rate alternately switching during a test. Small specimens are easy to carry and it is effective especially for geophysical researches in foreign countries. So, in this study, triaxial compression tests, noted above, were also conducted with rocks obtained around the Three Gorges Reservoir in China.

Size effect and time dependency are observed in most rock or bedrock. A lot of researches have been performed on both of them up to now. However, many points have been left unsettled although they are considered to be important especially for long-term stability of a large structure.In this study, long-term slope stability around the Three Gorges reservoir was discussed considering both size effect and time dependency. There are still not so many researches in the size effect related to slope stability, and it is difficult to presume the relationships between the size effect and slope stability theoretically or experimentally. So, in this study the size effect was estimated by data analysis of apparent friction and nominal dimension of landslides occurred in the past.Time dependency concerning slope collapse or landslide is well known. If the time dependency is remarkable, just a relatively low stress can lead to gradual deformation and then final failure. For evaluating the stability of, for example, 100 years, it is necessary to understand time dependency of the rock. For this reason, the rock collected in situ was tested in laboratory to obtain the time dependency by the recently developed testing method with relatively small specimens.Overdesign factor required for long-term slope stability was calculated based on the size effect and the time dependency. The long-term slope stability around the Three Gorges reservoir was discussed based on the estimated overdesign factor.

Most rocks indicate some extent of visco-elastic properties or time dependency. For example, strength and Young's modulus increase with loading rate in uniaxial compression test. In creep test, strain increases with time though stress is maintained to be a predetermined value. This visco-elastic behaviour is especially notable in porous rocks such as tuff or weathered rocks.In this study, visco-elastic properties of porous rocks are shortly reviewed and a new physical model or a constitutive equation is proposed. The model consists of a spring and a dashpot. It is assumed that the constitutive equation formerly proposed by these authors can be applied to the spring. Viscosity of the dashpot is quite low before loading, and is increasing gradually with progress of loading. In creep testing at low stress level, strain of the dashpot corresponds to creep strain because the spring constant does not decrease meaningfully at the low stress level.The experimental results of muddy sandstone, Oya tuff, Tage tuff and Kawazu tuff were compared with the calculated results. It is found that stress-strain curve shows good coincidence between experimental and calculated results. Increase of strength and Young's modulus with loading rate is well simulated by the model. Most important results are that, even at low stress, strain of the dashpot is considerably larger than formerly considered. By this model, the difference of Young's moduli between air-dried and water saturated conditions is well simulated where the difference in Young's modulus is assumed to be the deference in strain of the dashpot. In water-saturated condition, strain of the dashpot increases more rapidly and then Young's modulus is relatively small.

The acidic internal pH environment, initial burst release and lack of targeting property are main limitations of poly(lactide-co-glycolide) (PLGA) nanoparticles for carrying proteins. In this study, ϵ-polylysine (ϵ-PL) was used as an anti-acidic agent and a protein protectant to prepare PLGA nanoparticles for the protein delivery. To obtain the liver-targeting capability, lactosylated PLGA (Lac-PLGA) was synthesized by conjugation of lactose acid to PLGA at both ends, and then used to prepare nanoparticles containing ϵ-PL by the nanoprecipitation method. Bovine serumal bumin (BSA), a negatively charged protein, was efficiently loaded into Lac-PLGA/ϵ-PL nanoparticles and exhibited significant decreased burst release in vitro, sustained release in the blood and increased liver distribution in mice after intravenous injections. The enhanced stability of BSA was due to its electrical interaction with ϵ-PL and the neutralized internal environment of nanoparticles. In conclusion, Lac-PLGA/ϵ-PL nanoparticle system can be used as a promising carrier for the negatively charged proteins.

INTRODUCTION Aspergillus parasiticus Speare and A. flavus Link are two major fungi species that produce aflatoxins in agricultural commodities, such as groundnut, corn and cottonseeds. Because of the potency of aflatoxins as carcinogens and the associated food and feed safety hazards, worldwide regulatory limits have been established for aflatoxins in food and animal feeds (van Egmond, 1995). Groundnut (Arachis hypogaea L.) is a major oilseed crop widely grown in tropical and subtropical regions of the world. Aflatoxin contamination of groundnut by A. flavus and A. parasiticus is a serious problem and has a tremendous impact on the global groundnut industry as well as posing public health risks (Anjaiah et al., 2006). Therefore, control of aflatoxin contamination is very crucial for food and feed safety. Bacteria have been investigated for antifungal and aflatoxin-inhibiting activity against A. flavus and