近红外光谱法在红曲菌固态发酵过程参数检测中的应用

研究了近红外光谱技术快速检测红曲菌固态发酵过程参数水分含量和pH值的可行性。针对传统基于间隔策略波长选择方法忽略非线性因素的缺点,采用一种基于最小二乘支持向量机(Least squares support vector machines,LS-SVM)非线性模型的波长筛选算法：联合区间最小二乘支持向量机(Synergy interval least squares support vector machines,siLS-SVM),并将新算法与相关系数法、iPLS算法、siPLS算法对比。实验结果显示,联合siLS-SVM算法和LS-SVM模型取得了最好的预测效果,水分含量、pH值的预测集相关系数(Rp)分别为0.962 1、0.976 1,预测均方根误差(RMSEP)分别为0.012 9、0.145 2,表明模型具有较好的拟合度和预测性能。应用近红外光谱法进行红曲菌固态发酵过程的水分含量和pH值的快速检测可行,该方法为进一步实现其过程参数的在线检测及发酵条件优化提供了技术基础。     

Rheo-optical near-infrared (NIR) spectroscopy study of low-density polyethylene (LDPE) in conjunction with projection two-dimensional (2D) correlation analysis

A rheo-optical characterization technique based on near-infrared (NIR) spectroscopy is developed specifically to probe the submolecular-level deformation caused during a mechanical test. An illustrative example of the mechanical deformation of low-density polyethylene (LDPE) is provided to show how it can be utilized. A set of NIR spectra of the polymer sample were collected by using an acousto-optic tunable filter (AOTF) NIR spectrometer coupled with a tensile testing machine as an excitation device. While the substantial level of variation of spectral intensity was readily captured during the mechanical deformation of the LDPE, main feature of the NIR spectra was overwhelmed by the contribution from the baseline change. Projection 2D correlation analysis was then applied to selectively extract the signal contribution from the baseline fluctuation. The 2D correlation spectra revealed the predominant extension of amorphous tie chains followed by the rotation of crystalline lamellae, which induce elastic and plastic deformation of the LDPE, respectively.     

Effective Utilization of NIR Wavelengths for Photo‐Controlled Polymerization: Penetration Through Thick Barriers and Parallel Solar Syntheses

This contribution details an efficient and controlled photopolymerization regulated by far‐red (λ=680 nm) and NIR (λ=780 and 850 nm) light in the presence of aluminium phthalocyanine and aluminium naphthalocyanine. Initiating radicals are generated by photosensitization of peroxides affording an effective strategy that provides controlled polymerization of a variety of monomers with excellent living characteristics. Critically, long wavelength irradiation provides penetration through thick barriers, affording unprecedented rates of controlled polymerization that can open new and exciting applications. Furthermore, a more optimized approach to performing solar syntheses is presented. By combining the narrow Q‐bands of these photocatalysts with others possessing complementary absorptions, layered, independent polymerizations and organic transformations may be performed in parallel under a single broadband emission source, such as sunlight.     

Real‐Time In Vivo Detection of Cellular Senescence through the Controlled Release of the NIR Fluorescent Dye Nile Blue

In vivo detection of cellular senescence is accomplished by using mesoporous silica nanoparticles loaded with the NIR‐FDA approved Nile blue (NB) dye and capped with a galactohexasaccharide ( S3 ). NB emission at 672 nm is highly quenched inside S3 , yet a remarkable emission enhancement is observed upon cap hydrolysis in the presence of β‐galactosidase and dye release. The efficacy of the probe to detect cellular senescence is tested in vitro in melanoma SK‐Mel‐103 and breast cancer 4T1 cells and in vivo in palbociclib‐treated BALB/cByJ mice bearing breast cancer tumor.     

基于遗传算法的波长选择方法在绿茶近红外光谱分析模型中的应用

利用遗传算法(GA)提取茶叶的近红外吸收特征波长的方法,研究建立了绿茶水分和氨基酸的近红外分析模型,并对波长选择前后两种成分的模型进行了比较分析。结果表明,经遗传算法波长选择后,简化了分析模型,同时模型的稳健性增强。氨基酸预测集的均方根误差(SEP)减小82.1%,水分预测集的均方根误差减小(SEP)76.6%,它们在波长选择前后对应的分析波长数之比分别为995∶7和1990∶33。     

近红外光谱分析技术

介绍了近红外光谱分析技术的工作原理,阐述了其数学模型的建立及分析过程,总结了现有常用的化学计量学方法及各自的优点,最后简单的概括了近红外光谱分析技术的应用,尤其是在制药方面的应用.     

局部偏最小二乘回归建模参数对近红外检测结果的影响研究

报道了在局部加权(LWR)回归方法基础上,自主改进的更简单、实用的局部偏最小二乘回归(LPLS)的原理和方法。并以云南优质烤烟为实验材料,在国产光栅漫反射型近红外仪器上,研究了主成分数以及局部建模样品数对检测结果的影响。结果表明：应用交叉验证方法推荐的尼古丁组分模型主成分数并不是最优,通过适当降低主成分数可提高检测效果;局部建模样品数为30～50个时总糖、总氮、尼古丁预测准确度的提高幅度可分别达7%,14%,10%以上。该方法能有效提高近红外数学模型的预测准确度,是建立具有高度适应性近红外数学模型的有效方法。     

SIMCA法判别分析木材生物腐朽的研究

木材是一种生物质材料,容易受到各种微生物的危害,生物腐朽可以迅速导致木材结构的破坏,因此,对木材生物腐朽的快速、准确地检测或鉴定具有重要意义。近几年来,近红外光谱和SIMCA方法正被用于识别或检测食品、药品和农产品等研究中,因此,本研究尝试利用近红外光谱结合SIMCA方法来检测木材的生物腐朽。研究结果表明,应用近红外光谱和SIMCA方法能有效地判别木材的生物腐朽类型,通过培训集样本建立的基于PCA分析的SIMCA判别模型对未腐朽、白腐和褐腐三种类型样本进行回判,判别准确率分别为100%, 82.5%和100%;而对未知腐朽类型的样本(包括未腐朽、白腐和褐腐样本),判别准确率分别为100%, 85%和100%;SIMCA方法对未腐朽和褐腐类型的判别准确率均达到100%,但对白腐样本都有错判,造成这种错判的主要原因可能是由于样本包括的信息不够丰富以及腐朽初期白腐和褐腐试样的性质差异太小等。     

光程对黄酒金属元素近红外透射光谱分析精度的影响

应用近红外透射光谱分析技术开展了不同光程对黄酒中金属元素(钾、钙、镁、锌和铁)分析结果影响的研究。实验采用傅里叶变换近红外光谱仪(800～2 500 nm)及不同光程(1,2,5,10 mm),石英比色皿以空气为参比进行了光谱采集,并采用偏最小二乘法进行了数据分析。金属含量采用原子吸收光谱分析法测定。分析结果表明, 5 mm光程的分析结果最优,对于钾、钙、镁、锌和铁的相关系数(r2)分别为0.93,0.85,0.93,0.72,0.66,交互验证误差(RMSECV)分别为26.5,35.6,4.63,0.26,0.64 mg·L-1;而10 mm光程的光谱分析结果最差,其r2分别为0.61,0.65,0.63,0.09,0.25。通过实验说明, 光程对近红外透射光谱分析的影响,不是光程越长或越短越好,需要通过测试及对比分析确定。     

具有聚集诱导发光性质的近红外荧光染料

聚集诱导发光(AIE)现象的发现为解决传统有机荧光分子在高浓度和聚集形态下存在的荧光猝灭问题提供了最佳方案,并实现了在光电器件、化学传感、生物成像和靶向治疗等众多领域的广泛应用.随着对AIE 发光机理研究的不断深入,AIE 分子体系得到了极大的扩展.其中,一类具有给体-受体结构的AIE分子能够显著降低分子能隙,使发光分...