Sounds Stimulation on In Vitro HL1 Cells: A Pilot Study and a Theoretical Physical Model

Mechanical vibrations seem to affect the behaviour of different cell types and the functions of different organs. Pressure waves, including acoustic waves (sounds), could affect cytoskeletal molecules via coherent changes in their spatial organization and mechano-transduction signalling. We analyzed the sounds spectra and their fractal features. Cardiac muscle HL1 cells were exposed to different sounds, were stained for cytoskeletal markers (phalloidin, beta-actin, alpha-tubulin, alpha-actinin-1), and studied with multifractal analysis (using FracLac for ImageJ). A single cell was live-imaged and its dynamic contractility changes in response to each different sound were analysed (using Musclemotion for ImageJ). Different sound stimuli seem to influence the contractility and the spatial organization of HL1 cells, resulting in a different localization and fluorescence emission of cytoskeletal proteins. Since the cellular behaviour seems to correlate with the fractal structure of the sound used, we speculate that it can influence the cells by virtue of the different sound waves’ geometric properties that we have photographed and filmed. A theoretical physical model is proposed to explain our results, based on the coherent molecular dynamics. We stress the role of the systemic view in the understanding of the biological activity.     

基于GA-BP的汽车风振噪声声品质预测模型

目前对于汽车风振噪声的优化研究主要以声压级（Sound pressure level，SPL）作为单一评价指标，既不能全面反映噪声的物理属性，也无法考虑人耳对噪声的主观认知过程。为准确评价风振噪声，引入声品质，运用大涡模拟（Large eddy simulation，LES）对风振噪声进行数值仿真，根据实车道路试验判断仿真的准确性；对仿真结果进行声品质客观评价与主观评价，综合声品质客观评价参数与声品质主观评价试验结果建立BP神经网络预测模型；利用遗传算法（Genetic algorithm，GA），进一步对BP神经网络的结构参数进行优化，建立GA-BP声品质预测模型。研究结果表明，GA-BP声品质预测模型在训练速度和预测精度上都优于BP神经网络预测模型。预测模型基于声品质主客观评价结果，其预测值可以代替传统的声压级评价指标，为风振噪声提供更为准确合理的评价。     

Improving water retention of chicken breast meats by CaCl2 combined with pulsed electric fields

Frozen poultry meat is the most widely consumed animal-based food. However, water loss often leads to quality loss of poultry meat. Therefore, the present study sought to investigate the combined effect of calcium chloride (CaCl₂) and pulsed electric fields (PEF) treatment on chicken breast meats and the mechanisms underlying protein degradation. The results showed that the synergistic effect was superior to the single treatment. Compared with the untreated group, the combination of CaCl₂ and PEF increased water holding capacity of chicken breast meats by 16.61% and decreased cooking loss by 28.93%. Low-field nuclear magnetic resonance (LF-NMR) results indicated that the synergistic treatment promoted water molecules' binding capacity in myofibrils of poultry meat, which exhibited higher immobilised water. Additionally, the combination of CaCl₂ and PEF led to increased degradation of proteins of high-molecular weight and surface hydrophobicity of myofibrillar protein. Furthermore, the extension of the protein molecule and microenvironmental changes promoted interaction between protein and water. In conclusion, the synergistic treatment of CaCl₂ and PEF enhanced water retention and improved physicochemical properties of the myofibrillar protein in chicken breast meats.     

Pulsed Electromagnetic Field Stimulation in Osteogenesis and Chondrogenesis: Signaling Pathways and Therapeutic Implications

Mesenchymal stem cells (MSCs) are the main cell players in tissue repair and thanks to their self-renewal and multi-lineage differentiation capabilities, they gained significant attention as cell source for tissue engineering (TE) approaches aimed at restoring bone and cartilage defects. Despite significant progress, their therapeutic application remains debated: the TE construct often fails to completely restore the biomechanical properties of the native tissue, leading to poor clinical outcomes in the long term. Pulsed electromagnetic fields (PEMFs) are currently used as a safe and non-invasive treatment to enhance bone healing and to provide joint protection. PEMFs enhance both osteogenic and chondrogenic differentiation of MSCs. Here, we provide extensive review of the signaling pathways modulated by PEMFs during MSCs osteogenic and chondrogenic differentiation. Particular attention has been given to the PEMF-mediated activation of the adenosine signaling and their regulation of the inflammatory response as key player in TE approaches. Overall, the application of PEMFs in tissue repair is foreseen: (1) in vitro: to improve the functional and mechanical properties of the engineered construct; (2) in vivo: (i) to favor graft integration, (ii) to control the local inflammatory response, and (iii) to foster tissue repair from both implanted and resident MSCs cells.     

热定形对并列复合再生聚酯短纤维性能的影响

以再生聚酯瓶片料和泡料混合料为原料进行并列复合纺丝,并经后纺工艺处理得到并列复合再生聚酯短纤维。通过对纤维进行干热定形,研究热定形温度、时间对并列复合再生聚酯短纤的强伸性能、卷曲性能和热收缩性能的影响。结果表明:聚酯短纤维的断裂强度和断裂伸长率随着热定形温度升高而增大;断裂强度随热定形时间的延长逐渐下降,断裂伸长率先增大后减小,在20 min时达到最大值,为17.4%,声速取向因子则随着热定形时间的延长呈现下降趋势。纤维的卷曲性能随着热定形温度的升高而改善,较短的时间内,纤维的卷曲性能已经达到最佳;热定形温度的升高使纤维的热收缩率增大;并列复合再生聚酯短纤维的最佳热定形温度是140～160℃,最佳定形时间为10 min。     

Enhanced airborne sound absorption effect in poly(vinylidene fluoride)/(K0.5Na0.5)NbO3-nanofiber composite foams

Introducing electrical conductive function to discharge local piezoelectric effect is found effective for improving airborne sound absorption performance. In this work, instead of conductive fillers, a composite with two piezoelectric materials with opposite piezoelectric responses was explored aiming at enhanced sound absorption effect. Open-cell poly(vinylidene fluoride)/(K_0.5Na_0.5)NbO₃ (PVDF/KNN)-nanofiber composite foams were proposed and investigated for airborne sound absorption purpose. Structural and thermal analyses showed that the KNN nanofibers were well dispersed in the PVDF matrix and enhanced the degree of crystallinity of polar phase of PVDF. Significantly enhanced airborne sound absorption over a broad frequency range was observed in the PVDF/KNN-nanofiber composite foams, with increasing KNN nanofibers. One possible mechanism for the improved sound absorption with the piezoelectric KNN nanofibers with positive piezoelectric coefficient added in the PVDF matrix with negative piezoelectric coefficient is that electrical discharge could be facilitated for energy dissipation with the opposite charges generated through the piezoelectric effects in the two phases with opposite polarity. The experimental results show that the open-cell PVDF/KNN-nanofiber composite foams are promising for broadband airborne sound absorption application, and our analysis shed a light on the strategy in designing piezoelectric composite foam with high sound absorption performance.     

基于条件随机场的地质矿产文本分词研究

中文与英文不同,词与词之间没有类似空格的天然分隔符,致使中文分词成为中文信息处理中的难题。地质矿产文本中含有大量未登录地质专业术语,现阶段仍无效果较好的分词方法。本文探讨了一种基于双语料库条件随机场模型的方法对地质矿产文本进行分词,并与通用领域分词方法、单语料库条件随机场模型分词方法进行对比实验。实验表明,本文提出的方法在开放测试下分词效果明显优于其他方法,准确率为94.80%,召回率为92.68%,F-值为93.73%。本文对地质矿产文本进行了中文分词研究,既能够很好地识别未登录地质专业术语,又保证了普通词汇的识别率,为对地质领域的自然语言处理工作奠定了基础。     

硅溶胶/植物纤维吸声材料的制备及其性能研究

本研究提出一种以硅溶胶和杉木纤维为原料、采用泡沫成形法快速制备硅溶胶/植物纤维吸声材料的方法。结果表明,采用泡沫成形可以实现高蓬松度植物纤维基吸声材料的制备。另外,硅溶胶能够显著改善硅溶胶/植物纤维吸声材料的热稳定性和强度,与未添加硅溶胶的样品相比,当硅溶胶添加量为8%时,硅溶胶/植物纤维吸声材料的密度仅为20.21 kg/m3,而弹性模量和屈服强度分别从15.4 kPa和1.6 kPa提高到了86.2 kPa和4.4 kPa;硅溶胶/植物纤维吸声材料对5000 Hz以上声波的吸声系数达到了0.65。     

月桂酸乙酯的液相音速测量

脂肪酸甲酯(FAMEs)、脂肪酸乙酯(FAEEs)是生物柴油中的重要成分,为了计算发动机燃油喷射角度,需要获取生物柴油组分的音速。利用动态光散射法,在0.1、2.0、4.0、6.0、8.0 MPa下测量了月桂酸乙酯的液相音速,温度为295.15～353.15 K。为满足工程应用需求,根据实验数据,给出了月桂酸乙酯音速与温度和压力的关联式。在实验温、压范围内,实验值与关联式计算值的相对偏差绝对平均值为0.32%。     

A novel flow field with controllable pressure gradient to enhance mass transport and water removal of PEM fuel cells

An easily machined novel flow field with controllable pressure gradient across adjacent channels was designed and a two dimensional, across-the-channel, two-phase model was developed to study the gas transport and water removal of the novel configuration. The effect of channel-rib width ratio, GDL thickness and pressure gradient on the profiles of oxygen concentration and water saturation within the GDL were investigated. Special attention was paid to the mechanisms of the promoted mass transport and water removal rates under a pressure gradient. The model was validated by experiments with various channel-rib ratios and GDL thicknesses at different operating pressure. The results revealed that, oxygen concentration was increased, and the water saturation was reduced under the rib with a pressure gradient generated across the adjacent channels. The optimal pressure gradient is between 0.1 to 0.2 atm for the studied channel geometry and configuration. The mechanisms of the improved cell performance were elucidated.