PDMS在阶跃应变中松弛模量与动态剪切中广义弹性模量的比较

本文采用旋转流变仪对比研究了聚二甲基硅氧烷(PDMS)在两平行板间的动态剪切流动和阶跃应变的关系,应用Cho等人提出的应力分解方法考察了大振幅剪切流中的广义弹性模量,发现在线性区及非线性区的一部分,随着角频率ω的增加,在时间尺度为t=1/ω时,大振幅剪切流中的广义弹性模量逐渐接近阶跃应变中的松弛模量。     

Sigma-2 receptor ligand anchored telmisartan loaded nanostructured lipid particles augmented drug delivery,cytotoxicity, apoptosis and cellular uptake in prostate cancer cells

Recently, the anticancer activity of telmisartan (TEL) has been discovered against prostate cancer. Nevertheless, despite favorable therapeutic profile, poor aqueous solubility and suboptimal oral bioavailability hamper the anticancer efficacy of TEL. Therefore, in this investigation, sigma-2 receptor ligand, 3-(4-cyclohexylpiperazine-1-yl) propyl amine (CPPA) anchored nanostructured lipid particles of telmisartan (CPPA-TEL-NLPs) were engineered using stearic acid for targeting prostate cancer, PC-3 cells. The mean particle size of TEL-NLPs was measured to be 25.4?±?3.2?nm, significantly (p?p?p?In vitro drug release study was conducted to determine the drug delivery potential of tailored nanoparticles. TEL-NLPs released 93.36% of drug significantly (p?50 of CPPA-TEL-NLPs was measured to be 20.3?µM significantly (p?50 of 41.3?µM, significantly (p?>?0.05) not different from 43.4?µM, exhibited by TEL-NLPs in PNT-2 cells. We elucidated that CPPA-TEL-NLPs entered the PC-3 cells via receptor mediated endocytosis pathway and thus exhibited superior cytotoxicity, apoptosis and greater extent of cellular uptake in PC-3 cells. In conclusion, CPPA-TEL-NLPs may be a promising nanomedicine and warrant further in vivo investigations for gaining clinical success.     

Three‐Dimensional Exploration and Mechano‐Biophysical Analysis of the Inner Structure of Living Cells

A novel mechanobiological method is presented to explore qualitatively and quantitatively the inside of living biological cells in three dimensions, paving the way to sense intracellular changes during dynamic cellular processes. For this purpose, holographic optical tweezers, which allow the versatile manipulation of nanoscopic and microscopic particles by means of tailored light fields, are combined with self‐interference digital holographic microscopy. This biophotonic holographic workstation enables non‐contact, minimally invasive, flexible, high‐precision optical manipulation and accurate 3D tracking of probe particles that are incorporated by phagocytosis in cells, while simultaneously quantitatively phase imaging the cell morphology. In a first model experiment, internalized polystyrene microspheres with 1 μm diameter are three‐dimensionally moved and tracked in order to quantify distances within the intracellular volume with submicrometer accuracy. Results from investigations on cell swelling provoked by osmotic stimulation demonstrate the homogeneous stretching of the cytoskeleton network, and thus that the proposed method provides a new way for the quantitative 3D analysis of the dynamic intracellular morphology.     

Substrate-induced phenotypic switches of human smooth muscle cells: an in vitro study of in-stent restenosis activation pathways

In-stent restenosis is a clinical complication following coronary angioplasty caused by the implantation of the metal device in the atherosclerotic vessel. Histological examination has shown a clear contribution of both inflammatory and smooth muscle cells (SMCs) to the deposition of an excess of neointimal tissue. However, the sequence of events leading to clinically relevant restenosis is unknown. This paper aims to study the phenotype of SMCs when adhering on substrates and exposed to biochemical stimuli typical of the early phases of stent implantation. In particular, human SMC phenotype was studied when adhering on extracellular matrix-like material (collagen-rich gel), thrombus-like material (fibrin gel) and stent material (stainless steel) in the presence or absence of a platelet-derived growth factor (PDGF) stimulus. Cells on the collagen and fibrin-rich substrates maintained their contractile phenotype. By contrast, cells on stainless steel acquired a secretory phenotype with a proliferation rate 50 per cent higher than cells on the natural substrates. Cells on stainless steel also showed an increase in PDGF-BB receptor expression, thus explaining the increase in proliferation observed when cells were subject to PDGF-BB stimuli. The stainless steel substrate also promoted a different pattern of β1-integrin localization and an altered expression of hyaluronan (HA) synthase isoforms where the synthesis of high-molecular-weight HA seemed to be favoured. These findings highlighted the induction of a phenotypic pattern in SMC by the stainless steel substrate whereby the formation of a HA-rich neointimal tissue is enhanced.     

碳纳米管聚合物复合材料弹性模量预测模型研究进展

碳纳米管具有优异的力学、电学、光学和磁学等性能,是聚合物复合材料理想的增强体。弹性模量是材料重要的力学性能参数之一,本文介绍了近年来碳纳米管聚合物复合材料弹性模量的研究状况,综述了混合法则、Hashin-Shtrikman模型、Cox模型、Halpin-Tsai模型和数值模拟法预测碳纳米管聚合物复合材料弹性模量的方法,并提出了研究中面临的一些问题以及发展方向。     

Facile development,characterization, and evaluation of novel bicalutamide loaded pH-sensitive mesoporous silica nanoparticles for enhanced prostate cancer therapy

It is a challenge to deliver therapeutics exclusively to cancer cells, while sparing the normal cells. However, pH-sensitive delivery systems have proved to be highly efficient in fulfilling this task due to their ability to provide on-demand and selective release of drug at acidic tumor sites. As a proof of concept, here pH responsive drug delivery system based on mesoporous core shell nanoparticles (NPs) surrounded with poly acrylic acid (PAA) layers were prepared employing a facile synthesis strategy. Bicalutamide (BIC) was encased into surface functionalized MCM-41 nanoparticles via electrostatic interactions. The synthesized NPs were characterized by nitrogen adsorption and desorption isotherms, SEM-EDS, TEM, LXRD, and WXRD. In vitro release studies demonstrated that BIC-MSN-PAA NPs exhibited a higher release in the acidic media which varied inversely with the increase in pH. Further, the results of cell cytotoxicity assay were evident that BICMSNs exhibited more potent killing of both PC-3 and LNCaP cells than free BIC. PAA-MSNs also exhibited an enhanced cellular uptake and prolonged circulation time in vivo. The results are suggestive of the fact that PAA functionalized MSNs can serve as an effective pH-responsive template and hold a great potential ahead in controlled release and effective cancer treatment.     

Further developments in testing and analysis of the plate twist test for in-plane shear modulus measurements

The plate twist test for testing the in-plane shear modulus of composite materials is analysed. In the proposed test set-up the loads are not applied to the corners of the plate. This makes the test easier to perform than the original plate twist test. Based on a strength of materials approach, an analytical expression is found for the correction factor that accounts for the shifted position of the loading points. The analysis is made without making the assumption of equal bending stiffness in the diagonal directions of the plate, and can thus be applied for off-axis tests on orthotropic or lower symmetry composite materials.     

10CrNiMo结构钢弹性模量在低周疲劳过程中的变化规律

采用横截面为圆形的光滑试样,在六级轴向系列不同恒应变幅(0.3%~1.0%)控制下,研究10CrNiMo结构钢弹性模量在低周疲劳过程中的变化规律.结果显示:在不同级别应变幅控制下,随着应变幅值的增加,稳定循环下的弹性模量并不是恒量,而是以负幂指数函数规律减小,且最小与最大应变幅下的弹性模量相差超过15%;而在某一恒应变幅控制下的稳定循环区间内,弹性模量随着循环次数的增加而缓慢下降,但在疲劳失稳时,弹性模量迅速大幅降低.分析认为,出现上述现象的原因,与不同应变幅对材料造成不同程度的疲劳损伤及恒定应变幅控制下材料固有的持续疲劳抗力有关.     

Biogenic silver embedded magnesium oxide nanoparticles induce the cytotoxicity in human prostate cancer cells

This work reports the synthesis, characterization, and cytotoxicity of biogenic magnesium oxide nanoparticles (MgONPs) and nanosilver embedded magnesium oxide nanoparticles (Ag-MgONPs). The formation of nanoparticles (NPs) was confirmed by the indications of color changes and precipitations. Field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD) pattern studies showed the agglomeration colloids, porous, spherical, needle-shaped and crystal nature of MgONPs, whereas, the Ag-MgONPs was hexagonal, and spherical structured nanocrystals. Energy-dispersive X-ray fluorescence spectrometry (EDS) study indicated the existence of Ag, Mg, and O in NPs complex. The particle size analysis (PSA) revealed the mean size of 15.09?nm for Ag-MgONPs and 13.68?nm for MgONPs. Fourier transform infrared spectroscopy (FTIR) showed the peaks corresponding to amide, carboxylic acids, aromatics, alkene and esters from mycelial cell-free extract (MCFE). The absorbed and lattices oxygen of MgO was probably assigned in the formation of Ag-MgONPs as indicated by X-ray photoelectron spectroscopy (XPS). Cytotoxicity assay showed the Ag-MgONPs was stronger in inducing the prostate cancer (PC-3) cell death than the MgONPs. This work concluded that Ag-MgONPs could be potential therapeutics for cancer therapy.     

Development of drug-loaded chitosan hollow nanoparticles for delivery of paclitaxel to human lung cancer A549 cells

In this study, biodegradable chitosan hollow nanospheres (CHN) were fabricated using polystyrene nanospheres (PS) as templates. CHN were applied to increase the solubility of poorly water-soluble drugs. The lung cancer drug paclitaxel (PTX), which is used as a model drug, was loaded into CHN by the adsorption equilibrium method. The drug-loaded sample (PTX-CHN) offered sustained PTX release and good bioavailability. The state characterization of PTX by differential scanning calorimetry (DSC), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that the PTX absorbed into CHN existed in an amorphous state. An in vitro toxicity experiment indicated that CHN were nontoxic as carriers of poorly water-soluble drugs. The PTX-CHN produced a marked inhibition of lung cancer A549 cells proliferation and encouraged apoptosis. A cell uptake experiment indicated that PTX-CHN was successfully taken up by lung cancer A549 cells. Furthermore, a degradation experiment revealed that CHN were readily biodegradable. These findings state clearly that CHN can be regarded as promising biomaterials for lung cancer treatment.     

Investigation of the Young''s modulus of TiB needles in situ produced in titanium matrix composite

In situ Ti/TiB composites with different volume fractions of discontinuous TiB reinforcements were produced by powder metallurgy. After compacting Ti+TiB₂ powders by hot unidirectional pressure, heat treatments led to the in situ formation of distinctive needles of TiB, randomly distributed in the titanium matrix. The Young's modulus of TiB was evaluated using the ASW computation method and experimental Vickers micro-indentation. Three point bend tests were performed on Ti/TiB composites as a function of the TiB volume fraction in order to extract the Young's modulus of TiB from the elastic properties of the composite. The different values obtained according to these three methods were discussed and compared with the literature.     

Numerical modelling of the scattering of elastic waves in plates

This paper describes the application of finite difference methods to the calculation of the scattering of elastic waves. The emphasis is on cracklike defects in plates, and it is shown that a common numerical technique can span a range of wavelengths from Lamb waves to ultrasonic waves with many reflections from the surfaces of the plate. Quantitative results are given for the scattering of Lamb waves and ultrasonic shear waves from surface-breaking cracks.     

琼斯矩阵在分布式光纤传感器偏振态分析中的应用

针对基于Sagnac原理的分布式光纤传感器中光波偏振态在双折射影响下所带来的干涉信号"偏振诱导衰落"问题,运用琼斯矩阵分析法,建立了传输光偏振态影响系统功率传输系数的数学模型;根据仿真分析的结果,发现使用反射镜作为反射元件,只能消除光纤圆双折射的影响,而不能消除线性双折射的影响.因此,提出了使用法拉第旋转镜提高系统抗偏振衰落能力的改进方法,仿真结果表明可以很好地消除传感光纤的线性双折射和圆双折射的影响.     

Evaluation of transverse Poisson's ratios in thin orthotropic plates by the optical method of pseudocaustics

An analytical treatment of the optical mapping produced by deviated light rays impinging on a perforated orthotropic plate revealed the possibility of proceeding to a direct measurement of transverse Poisson's ratios. This was accomplished theoretically by correlating the transverse, D_t, and longitudinal, D₁, diameters of the pseudocaustic curve created by the boundary of an elliptic opening in a uniaxially tensioned plate of an orthotropic material with the transverse components of the compliance tensor. The theoretical foundation of the method was based on the exact closed-form solution of the geometry under consideration given by Lekhnitskii and Savin.

It was shown that both the dimensions and the shape of the pseudocaustic curve are drastically affected by changes in the values of transverse Poisson's ratios. Thus, the method constitutes a powerful and perhaps unique device for evaluating characteristic parameters related to the thickness of the plate representing the stress field by measuring characteristic lengths along a plane parallel to the middle plane of the plate. Finally, by means of the proposed method one can readily establish the local material principal directions for a solid plate of unknown elastic symmetry and directions of principal axes.     

An in silico study on the role of smooth muscle cell migration in neointimal formation after coronary stenting

Excessive migration and proliferation of smooth muscle cells (SMCs) has been observed as a major factor contributing to the development of in-stent restenosis after coronary stenting. Building upon the results from in vivo experiments, we formulated a hypothesis that the speed of the initial tissue re-growth response is determined by the early migration of SMCs from the injured intima. To test this hypothesis, a cellular Potts model of the stented artery is developed where stent struts were deployed at different depths into the tissue. An extreme scenario with a ruptured internal elastic lamina was also considered to study the role of severe injury in tissue re-growth. Based on the outcomes, we hypothesize that a deeper stent deployment results in on average larger fenestrae in the elastic lamina, allowing easier migration of SMCs into the lumen. The data also suggest that growth of the neointimal lesions owing to SMC proliferation is strongly dependent on the initial number of migrated cells, which form an initial condition for the later phase of the vascular repair. This mechanism could explain the in vivo observation that the initial rate of neointima formation and injury score are strongly correlated.     

Formulation-optimization of solid lipid nanocarrier system of STAT3 inhibitor to improve its activity in triple negative breast cancer cells

In the present study, solid lipid nanoparticles (SLNs) have been formulated as a carrier system for effective intracellular delivery of STAT3 inhibitor, niclosamide (Niclo) to triple negative breast cancer (TNBC) cells. Emulsification-solvent evaporation method was employed in formulation of Niclo-loaded SLNs (Niclo-SLNs). The formula of Niclo-SLN was optimized by Box–Behnken design and characterized for their shape, size, and surface charge. The in vitro anti-cancer efficacy of Niclo-SLNs was studied in TNBC cells. The prepared Niclo-SLNs were found to be spherical with the particle size of 112.18?±?1.73?nm and zetapotential of 23.8?±?2.7?mV. In the in vitro anticancer study the Niclo SLNs show a better cytotoxicity than the naïve Niclo, which is attributed to improved cell uptake of SLN formulation. In conclusion, the results of the present study demonstrate that the formulation of Niclo as SLNs will improve the anticancer efficacy against TNBC.     

Comparative enhancement of curcumin cytotoxic photodynamic activity by nanoliposomes and gold nanoparticles with pharmacological appraisal in HepG2 cancer cells and Erlich solid tumor model

Curcumin is a natural pigment that generates singlet oxygen upon light excitation, hence it can be used as a photosensitizer in photodynamic therapy. The extremely low water solubility and poor systemic bioavailability make curcumin a challenging molecule to be used clinically. In this study, two nanocarrier systems for curcumin were prepared and characterized; nanoliposomes and polyvinyl pyrrolidone-capped gold nanoparticles. The dark and photocytotoxicity were investigated as a function of light fluence rate (100 and 200?mW/cm²) on HepG2 cancer cells. In vivo Erlich tumor model was developed and comparison of the tumor volume, survival rate, and histopathological alterations was made for the two nanocarriers. Results showed that both curcumin nanocarriers were successfully prepared and characterized. Light irradiation was able to augment the cytotoxicity of both curcumin liposomes and gold nanoparticles, with the former being superior in cytotoxicity compared to the latter. The tumor size was almost diminished 1 month post-photodynamic treatment for both systems with regression in the number of tumor cells upon histopathological evaluation, with curcumin liposomes producing better tumor regression than gold nanoparticles with comparable survival rate. Liposomes were confirmed to be superior to gold nanoparticles as a photodynamic treatment modality for cancer.     

Application of high mobility transparent conductors to enhance long wavelength transparency of the intermediate solar cell in multi-junction solar cells

High mobility transparent conducting oxide (HMTCO) materials (mobility > 60 cm² V^− 1 s^− 1) have a high transmission over the visible to near infra red wavelength region with resistivity < 2 × 10^− 4 Ω cm. We investigate the application of HMTCO materials as transparent contacts for multi-junction and bifacial solar cells to increase the device NIR transmission. Using the HMTCO materials as front contacts significantly reduces absorption and reflection losses of the solar cells, from 850-1500 nm. The need to develop a low temperature process to prepare HMTCO materials as back contacts in semi-transparent solar cells is also emphasized.     

光谱响应测试在多结型太阳能电池中的应用

针对在高效率多结型硅薄膜元件结构设计中无法测出各层短路电流的困难,指出光谱响应／量子效率光谱测试在这方面的应用。利用该项技术,使电池各层在短路电流密度上达到最佳匹配,从而改进制程,提高电池的效率。     

The use of central reflection in the formulation of unit cells for micromechanical FEA

Central reflection as a type of symmetry has been exploited in the context of structural analysis for the first time in this paper, especially in terms of applications to the formulation of unit cells for micromechanical FE analysis of materials of periodic microstructures. It reduces the size of the unit cell to be analysed without compromising useful features of the unit cells obtained purely from periodic conditions, viz. the unit cell can still be analysed with a single set of boundary conditions under all loading conditions and any combined loading condition. Such a feature cannot be preserved if a conventional plane reflectional symmetry or a rotational symmetry has been used in order to reduce the size of the unit cell to be analysed. Most of existing unit cells obtained purely from periodic conditions can benefit from this further symmetry. Boundary conditions for unit cells of reduced sizes resulting from the use of the centrally reflectional symmetry have been derived rationally in this paper. They have been validated systematically through examples of applications.