纤维增强薄壁注塑件翘曲变形耦合有限元分析

基于耦合有限元分析方法，运用模流分析软件Moldflow和结构分析软件Abaqus进行联合仿真，计算了脱模后薄壁塑件的应力分布和翘曲变形情况，并通过对比验证了该方法的有效性，随后考察了主要工艺参数和壁厚对翘曲变形的影响。研究结果表明：随着翘曲变形的产生塑件内的残余应力随之减小；在考察的工艺参数范围内，壁厚是影响翘曲变形的主要因素，随着壁厚的增加，翘曲变形量减小，而工艺参数对翘曲变形的影响则相对较小；但随着壁厚持续增加，因塑件刚度的增加，壁厚对翘曲变形的影响程度随之减小。该结果与文献结论一致。     

Binding of Euplotes octocarinatus centrin with target peptide melittin

Interactions between model target peptide melittin (ME) and Euplotes octocarinatus centrin (EoCen) were investigated by fluorescence spectra, circular dichroism (CD) spectra and native polyacrylamide gel electrophoresis (PAGE). In 0.1 mol/L N-2-hydroxyethylpiperazine-N-2-ethanesulfonic acid (Hepes) and 150 mmol/L NaCl at pH 7.4, EoCen and isolated short C-terminal domain of EoCen (SC-EoCen) form 1:1 peptide:protein complexes. However, no detectable signal changes can be observed while isolated N-terminal domain of EoCen (N-EoCen) or isolated long C-terminal domain of EoCen (LC-EoCen) was added into solution of ME. The interaction between EoCen and ME is specified exclusively for the short C-terminal domain of EoCen. On the basis of fluorescence titration curves, the conditional binding constants of ME with EoCen and SC-EoCen were calculated to be logKME-EoCen = 6.81±0.33 and log- KME-SC-EoCen = 6.51±0.45, respectively.     

Influence of location-dependent protuberance damage on cell viability

The influence of femtosecond laser-induced damages on viability of olfactory ensheathing cells (OECs) is investigated. Several cytokinetic processes including cellular damage, recovery and death are discussed. Using femtosecond laser with the power of 100 μW and cutting speed of 2 μm/s, we cut the cellular protuberance with smaller diameter twice in different locations, and then observe the viability of the damaged cells. Under the same conditions, the root of protuberance with larger diameter is cut six times to observe changes of cellular shape. Whether the damage is located in the end, middle or root of protuberance with smaller diameter, the cell viability can recover within 3 h. When the damage is located in the root of protuberance with larger diameter, the damaged cell will die in the way of oncosis. Cytokinetic phenomena including intracellular high Ca²⁺ concentration, cellular morphologic change, recovery and oncosis are discussed. Meanwhile, high Ca²⁺ concentration is observed after femtosecond laser surgery. Therefore, femtosecond laser surgery is an important tool for establishing cell damage model and studying cytokinetics. Supported by National High Technology Research & Development Program of China (Grant No. 2006AA04Z307), Author of National Excellent Doctoral Dissertation of PR China (Grant No. 2006039), National Natural Science Foundation of China (Grant No. 50775104), Natural Science Foundation of Jiangsu Province (Grant No. BK2006507) and Jiangsu Provincial Research Innovation Program for College Graduates (Grant No. CX07B_086z)     

Metal ion-binding properties of wild-type and mutant D37K of ciliate Euplotes octocarinatus centrin

Ciliate Euplotes octocarinatus centrin (EoCen) is an EF-hand calcium-binding protein closely related to the prototypical calcium sensor protein calmodulin. The first amino acid of the Ca²⁺-binding loops found in the EF-hand calcium-binding proteins is a highly conserved aspartic acid residue. The D37K mutant was produced to elucidate the metal binding role of the first aspartic acid of the EF-loop I of EoCen. Aromatic-sensitized Tb³⁺ fluorescence results indicated that the metal binding ability of loop I was lost due to the D37K mutation. Based on fluorescence titration curves of Lu₂-D37K, the conditional binding constants of the EoCen loop II were quantitatively found to be K _II = (1.61 ± 0.04) × 10⁵ L mol^?1 and K _II = (3.52 ± 0.08) × 10² L mol^?1 with Tb³⁺ and Ca²⁺, respectively. Using 2-p-toluidinylnaphthalene-6-sulfonate as a hydrophobic probe, exposure of the hydrophobic surface upon metal binding was found to be significantly reduced for the metal ion-saturated EoCen D37K mutant.     

Synthesis, characterization and size control of zerovalent iron nanoparticles anchored on montmorillonite

Zerovalent iron nanoparticles have been successfully synthesized using sodium borohydride solution reduction of ferric trichloride hexahydrate in the presence of montmorillonite as an effective protective reagent and support as well. A combination of characterizations reveals that with high monodispersity these obtained iron nanoparticles are well dispersed on clay surface, virginal from boron related impurity, and oxidation resistant well with iron core-iron oxide shell structure. The shell thickness of 3 ...     

In vitro bioactivity and cytocompatibility of porous scaffolds of bioactive borosilicate glasses

The bioactive borosilicate scaffolds （R2O-RO-B2O3-SiO2-P2O5） with four different contents of borate were fabricated by replication technique. The bioactivity, degradability and the cytotoxicity of the scaffolds were studied in this paper. The porosity of the scaffolds was found to be 73%-80%, and the pore size was in the range of 200-300 μm. The porous scaffolds immersed in 0.02 mol.L^-1 K2HPO4 solution were transformed into hydroxyapatite. And it is notable that the D-AIk-2B, D-AIk-3B-scaffolds were covered by hydroxyapatite layers after 7 h-immersion, which proved their high bioactivity. In the cell adhesion test, cells could be seen growing well on the scaffolds, showing stretched morphology and obvious pseudopodia, and only the high cumulative concentration of B ions released from the D-AIk-3B-scaffold samples had an inhibition effect on cell proliferation. But the inhibition effect could be alleviated by diluting the extract solution to a certain concentration （dilution ratio： 1：8）. Therefore, after suitable pretreatment, the porous borosilicate bioactive glass scaffold can be a desirable candidate for bone tissue engineering.     

Preparation of bioactive glasses with controllable degradation behavior and their bioactive characterization

Bioactive glasses and ceramics have been widely investigated for bone repair because of their excel-lent bioactive characteristics. However, these biomaterials undergo incomplete conversion into a bone-like material, which severely limits their biomedical application. In this paper, borosilicate bioac-tive glasses were prepared by traditional melting process. The results showed that borosilicate glasses possessed high biocompatibility and bioactivity. In addition, when immersed in a 0.02 mol/L K2HPO4 solution, particles of a borate glass were fully converted to HA. The desirable conversion rate to HA may be achieved through the adjustment of the B2O3/SiO2 ratio. The results of XRD and FTIR analysis indicated that the degradation product was carbonate-substituted hydroxyapatite, which was similar to the inorganic component of bone.     

Nonlinear short-term heart rate variability prediction of spontaneous ventricular tachyarrhythmia

As malign ventricular tachyarrhythmias triggering sudden cardiac death （SCD）, both ventricular tachycardla （VT） and ventricular fibrillation （VF） are major causes of mortality. The most efficient therapy for SCD prevention is implantable cardioverter defibrillators （ICD）. The ICD can accurately and effectively Identify the forthcoming of fatal ventricular tachyarrhythmlas and deliver a shock in order to restore patients＇ normal sinus rhythm. In this study, two nonlinear complexity measures based on entropy： approximate entropy （ApEn） and sample entropy （SampEn） as well as two time linear indices： the mean RR interval （the average of time intervals between consecutive R-waves） and the standard deviation of RR Intervals were used for short-term forecasting of VT-VF occurrence. The last small sections of interbeat Intervals preceding 135 VT-VF episodes from 78 patients stored by the ICD were analyzed and compared with individually acquired control time series （CON series） from the same patients, which are normally intrinsic sinus rhythms. The results demonstrate that in addition to an obvious increase in heart rates of the patients, the values of two entropy measures are significantly smaller for VT-VF episodes than those for CON series. Conclusions can be drawn that when a ventricular tachyarrhythmia approaches, the sympathetic tone of the patients is increased, and the complexity of their RR intervals immediately before the onset of VT-VF events is obviously lower than that of RR intervals recorded during sinus rhythms. For a better separation, the optimal range of threshold r is determined for two algorithms. ApEn and SampEn measures might be the suitable nonlinear parameters for shodterm prediction of life-threatening ventricular tachyarrhythmias in the application of the cardioversion and defibrillation.     

Baculovirus-mediated expression of a Chinese scorpion neurotoxin improves insecticidal efficacy

An Buthus martensii Karsch Insect Toxin （BmK IT ） gene was inserted into the genome of Autographa californica multicapsid nucleopolyhedrovirus （AcMNPV） to construct a recombinant baculovirus, AcMNPV-BmK IT. The expression of BmK IT was confirmed using RT-PCR, dot blot and SDS-PAGE analysis. Dose-lethal time responses to Spodoptera exigua larvae were compared between wild-type baculovirus AcMNPV and recombinant virus AcMNPV-BmK IT. At the concentration of 1 × 10^7 PIBs/mL, the median lethal time of recombinant baculovirus （LT50 = 73.6 h） on third instar S. exigua larvae showed an improvement of 13.2% over the efficacy of wild type virus （LT50 = 84.8 h） during a 192 h infection.