超声辐照乳液聚合研究进展

综述了超声辐照乳液聚合的特点，聚合成核机理，影响因素及反应动力学特点，简要介绍了超声辐照无皂乳液聚合，超声辐照微乳液聚合，超声辐照乳液共聚和纳米粒子存在下的超声辐照乳液聚合。     

双频复合超声强化无水葡萄糖溶液结晶成核研究

溶液结晶技术在许多领域有着广泛的应用,其中结晶成核是溶液结晶的关键环节。以无水α-葡萄糖为研究对象,采用双频复合超声(25 k Hz+40 k Hz)强化糖液结晶成核,研究了溶液浓度、超声功率和作用时间对成核速率的影响,对单频和双频作用的晶核形态进行了对比,并采用碘化钾溶液中碘的释放量研究超声空化产额。研究结果表明:在同等条件下,双频复合超声降低了溶液成核的初始浓度,提高了成核速率,同时得到粒度均匀的晶核;双频复合超声的空化产额远高于单频25 k Hz超声和单频40 k Hz超声的空化产额,双频复合超声具有协同作用。双频复合超声强化溶液成核是一种快速、高效、节能的方法。     

超声技术在食品工业中的应用

超声作用的物理机制有热机制、机械机制和空化机制。它能加速质量、热量传递，缩短单元操作时间，提高操作效率；还能促进结晶成核、控制晶粒体粒径分布，改善食品的品质等。超声技术不仅可应用于食品的加工过程，如食品的提取、干燥、过滤、结晶、乳化、灭菌，还可应用于食品体系的检测、分析。文章简要介绍了超声作用的物理机制，重点论述了超声技术在食品加工及食品检测分析中的应用。     

超声在工业结晶的应用

超声在结晶过程中的应用,近几年引起了国内外学者的广泛兴趣,主要探讨超声对结晶过程中结晶溶液的诱导期、溶液的一次成核、二次成核、晶体的结晶速率以及晶体的形貌和结构的影响.发现超声可以缩短诱导期,加速晶核的生成.提高晶体的结晶速率,改变晶体的形貌.特别是对产品的影响,可以更好地满足人们对产品的要求.     

熔融温度对PP中成核剂的异相成核作用的影响

用DSC研究了熔融温度对不同类型成核剂成核PP的异相成核作用的稳定性的影响。观察到随熔融温度提高，纯PP的成核作用稳定，降温结晶温度基本不变。而有机磷酸盐类成核剂成核PP的结果温度比纯PP的高，而且异相成核作用受熔融温度的影响也很小。但山梨醇类成核剂成核PP的异相成核作用随熔融温度提高，结晶温度逐步降低明显，表明其异相成核作用对热不稳定。     

PA1010结晶的异相成核作用研究

通过引入成核剂（Ｎｄ２Ｏ３）研究ＰＡ１０１０微晶结构的变化，以及对ＰＡ１０１０结晶行为的影响，也讨论成核剂对结晶－非晶中间相的作用，利用ＷＡＸＤ，ＳＡＸＳ和ＤＳＣ手段，讨论了成核的异相成核作用。结果表明，成核剂明显改变了ＰＡ１０１０的微晶结构。     

有机磷类成核剂作用下聚丙烯结晶行为及其力学性能

研究了含有不同含量成核剂的聚丙烯的结晶行为对其力学性能的影响．结果表明，当成核剂含量从0增至0．8％(质量)时，树脂的拉伸强度和弯曲强度提高了15％，弯曲模量增加了35％，结晶温度提高了10℃，由非线性Volterra积分方程得到的成核密度提高了10^4倍，而且成核聚丙烯的成核密度与其材料的力学性能之间存在着线性关系，即随着成核密度的增大，材料的拉伸和弯曲性能呈线性的增大．     

CVD金刚石成核的最新研究

研究了化学气相条件下金刚石在非均匀研磨硅基底表面及镜面基底和均匀研磨基底边缘及角域处的成核行为。发现ＣＶＤ金刚石成核不仅依赖于沉积区缺陷，更主要由缺陷的锐度决定，即缺陷加强ＣＶＤ金刚石成核的锐度效应。在对无序碳上ＣＶＤ金刚石成核研究的基础上，讨论了ＣＶＤ金刚石成核的机理，并由此阐明了各种表面预处理及负偏压等增强ＣＶＤ金刚石成核的微观过程。     

CVD金则石薄膜的成核机理研究

利用热丝化学气相沉积，在预觉 无定形碳的硅镜面基底及表面研磨预处理的铜基底上，实现了金刚石膜的沉积，并由此讨论了金刚石的成核机理。研究表明，无定形碳是金刚石成核的前驱态；成核密度不仅与基底材料有关，更主要由基底的表面状态决定，基底表面状态的设计进改善成核密度的最有效的方法。     

新型弛豫铁电单晶PMNT的生长研究

新型弛豫铁电晶体(1-x)Pb(Mg1/3Nb2/3)-xPbTiO3是具有钙钛矿结构的固溶体材料,在医用超声成像、声纳、微位移器等方面具有广阔的应用前景.在坩埚下降法生长炉内,采用自发成核和通气诱导成核两种方法生长了0.67Pb(Mg1/3Nb2/3)-0.33PbTiO3晶体,尺寸分别达到Ф30mm×35mm和35mm×35mm×40mm.XRD分析表明,所得晶体为钙钛矿结构.比较研究了自发成核生长和通气诱导成核生长两种不同的生长工艺及其优缺点.     

Comparing the pozzolanic behavior of sugar cane bagasse ash to amorphous and crystalline SiO2

The present paper aims to clarify the pozzolanic behavior of sugar cane bagasse ash-SCBA by comparing it to amorphous and crystalline silica. It is shown that calcium silicate hydrate is formed in lime solution with SCBA but the reaction is slow and does not consume all the material. Comparing its results with the obtained in tests with silica fume and with crushed quartz show a better agreement with the latter. Characterization of cement pastes shows 20% of cement replacement by sugar cane bagasse ash leads to only a minor reduction in the amount of calcium hydroxide formed. This behavior is also closer to the observed in quartz than in silica fume. The results suggest SCBA should be used as a replacement for inert constituents in cement composites rather than pozzolanic addition. Analysis of the microstructure of the cement pastes revealed the presence of calcium hydroxide in samples prepared with partial replacement by silica fume, quartz and sugar cane bagasse ash. The presence of this phase in the sample prepared with silica fume was attributed to agglomeration of the particles that affected the reactivity of this material.     

甘蔗渣对聚甲基丙烯酸甲酯热降解的影响

目的分析生物质材料对塑料废弃物热降解的影响,以聚甲基丙烯酸甲酯(PMMA)为对象,探讨甘蔗渣对其热分解行为和动力学的作用。方法利用溶液共混法制备PMMA/甘蔗渣混合物,采用热失重法研究其在氮气中的热分解过程,通过最大失重速率法和Ozawa等失重法计算PMMA热分解反应的动力学参数活化能和频率因子。结果甘蔗渣使得PMMA的初期热分解温度明显降低,但是PMMA的热分解活化能和频率因子却都显著增加。最大失重速率法的计算结果表明,PMMA加入甘蔗渣后的热分解活化能增加了26.2 k J/mol,等失重法的结果显示活化能和频率因子分别为168.14 k J/mol和28.41 min-1,比纯PMMA相应地增大了72.6 k J/mol和12.52 min-1。结论甘蔗渣的加入对PMMA的热降解有显著的影响,使其热分解变得困难,因此有必要进一步探讨其他生物质对PMMA热分解的影响。     

鲜切山药保鲜护色研究

目的利用家用调味剂(蔗糖、食盐、白醋)对鲜切山药保鲜护色进行研究。方法利用L9(34)正交试验配置一定浓度的蔗糖、食盐、食醋复合浸渍液,并用聚乙烯薄膜进行包装,得出比较理想的鲜切山药贮藏方法。结果蔗糖、食盐、白醋都有很好的保鲜护色效果,单因素试验表明,当采用蔗糖、食盐、食醋(质量浓度分别为3,1,3 g/L)浸泡鲜切山药10 min后,其褐变度的减缓和PPO活性的抑制最为明显。正交试验结果表明,采用蔗糖、食盐、白醋质量浓度分别为4,2,3 g/L混合处理液浸泡10 min后,护色保鲜效果最好。结论经过特定浓度复配的蔗糖、食盐、白醋溶液能有效抑制鲜切山药的酶促褐变,起到保鲜护色的作用。     

Effects of calcining conditions on the microstructure of sugar cane waste ashes (SCWA): Influence in the pozzolanic activation

In this paper a study of calcining conditions on the microstructural features of sugar cane waste ash (SCWA) is carried out. For this purpose, some microparticles (<90 μm) of sugar cane straw ash and sugar cane bagasse ash of samples calcined at 800 °C and 1000 are studied by combining the bright field and the dark field images with the electron diffraction patterns in the transmission electron microscopy (TEM). It is appreciated that the morphology and texture of these microparticles change when silicon or calcium are present. Furthermore, it is observed that iron oxide (magnetite Fe₃O₄) is located in the calcium-rich particles.The microstructural information is correlated with the results of a kinetic–diffusive model that allows the computing of the kinetic parameters of the pozzolanic reaction (mainly the reaction rate constant). The results show that the sugar cane wastes ash calcined at 800 and 1000 °C have properties indicative of high pozzolanic activity. The X-ray diffraction patterns, the TEM images and the pozzolanic activity tests show the influence of different factors on the activation of these ashes.     

On the fatigue behaviour of quenched and tempered at 300 and 600 °C SAE 1045 steel in an environment of sugar cane juice

SAE 1045 steel is widely used for manufacturing shafts in the sugar cane mills of the sugar industry. These shafts are designed with an expectation of a long lifetime. However, fatigue failures occur frequently. The sugar cane juice processed in these mills has corrosive properties that can alter the fatigue life of these shafts. In this research, the fatigue strength of SAE 1045 steel between 1 × 10⁴ and 2 × 10⁵ cycles in air and in sugar cane juice, with two different microstructures (tempered martensite at 300 °C and tempered martensite at 600 °C), was determined in rotating bending. The microstructure of the materials was characterized using optical microscopy, and the fracture surfaces were characterized using scanning electron microscopy. The results show that the fatigue strength at 2 × 10⁵ cycles for the tempered condition at 600 °C decreases 7% because of the sugar cane juice effect, and for the tempered condition at 300 °C, the fatigue strength decreases 15%.     

Optimal reconfiguration of a sugar cane industry to yield an integrated biorefinery

The sugar cane production is one of the main economic activities of the agriculture sector in several places around the world. Nowadays, the sugarcane production zones face different technologic, economic, and social problems that impact negatively their profitability. The low price of sugar in the market demands the search of alternatives; being the bioethanol production from resides of the sugar cane industry an attractive option. This way, this paper presents a new approach for using the residues from the sugar cane industry to yield a sustainable biorefinery. In this approach, process integration techniques have been implemented to optimize the overall process. A case study from the State of Michoacán in Mexico is presented, where the proposed approach shows significant economic, environmental, and social benefits.     

Structural and thermal characterization of Moroccan sugar cane bagasse cellulose fibers and their applications as a reinforcing agent in low density polyethylene

Cellulose fibers were isolated from Moroccan sugar cane bagasse by using three distinct stages. Firstly bagasse was subjected to (1) a hot water (70 °C) treatment to eliminate hemicellulose, then to (2) an alkaline aqueous solution (15% of sodium hydroxide (NaOH), 98 °C) treatment to eliminate lignin, and finally to (3) a bleaching stage. Sugar cane bagasse cellulose fibers were analyzed by different complementary analysis (FT-IR; ¹³C NMR and TG). The reinforcing capability of cellulose fibers extracted from sugar cane bagasse was investigated using low density polyethylene as matrix. The cellulosic preparations were free of bound lignin. The intrinsic viscosity, the viscosity average and the molecular weight were respectively 511 ml/g, 1769 and 286578 g/mol. An enhance on mechanical properties of composites was found, a gain of 72% in Young’s modulus at 25 wt.% fiber loading and a gain of 85% in flexural modulus at 25 wt.% fiber loading, as a results of a good interface adhesion between cellulose fibers and matrix.     

Citric acid separation using a hollow fibre liquid membrane system

Citric acid is the bulk chemical produced in the largest volume by fermentation using Aspergillus niger in submerged cultures. It can be made from sugar cane juice, or cane or beef molasses, and acid concentrations up to around 15% can be achieved.     

Sugar Cane Bagasse Waste as Reinforcement in Low Cost Composites

The State University of the North of Rio de Janeiro State is currently engaged on a large development program to exploit the potentialities of sugar cane industry in a self sustained nonpolluting program. Sugar cane is a traditional industry responsible for the main fraction of the economy of the northern region of the State of Rio de Janeiro, also known as the North Fluminense region. In this respect, a project of particular interest is the use of the sugar cane bagasse waste as reinforcement to polymeric resins for fabrication of low cost composites. In the present work a study was carried out on the possible uses of bagasse waste as reinforcement in polyester matrix composites. Preliminary results have attested this possibility. Composites with homogeneous microstructures could be fabricated and the level of their mechanical properties enable them to have practical applications similar to the ones normally associated with wooden agglomerates. Future developments are expected to increase the performance and competitiveness of these composites as compared to those of other materials in the same structural class.     

Visible/near infrared-partial least-squares analysis of Brix in sugar cane juice: A test field for variable selection methods

Several variable selection algorithms were applied in order to sort informative wavelengths for building a partial least-squares (PLS) model relating visible/near infrared spectra to Brix degrees in samples of sugar cane juice. Two types of selection methods were explored. A first group was based on the PLS regression coefficients, such as the selection of coefficients significantly larger than their uncertainties, the estimation of the variable importance in projection (VIP), and uninformative variable elimination (UVE). The second group involves minimum error searches conducted through interval PLS (i-PLS), variable-size moving-window (VS-MW), genetic algorithms (GA) and particle swarm optimization (PSO). The best results were obtained using the latter two methodologies, both based on applications of natural computation. The results furnished by inspection of the spectrum of regression coefficients may be dangerous, in general, for selecting informative variables. This important fact has been confirmed by analysis of a set of simulated data mimicking the experimental sugar cane juice spectra.