Bleachability and characterization by fourier transform infrared principal component analysis of acetosolv pulps obtained from sugarcane bagasse

Sugarcane bagasse Acetosolv pulps were bleached by xylanase and the pulps classified by using Fourier transform infrared (FTIR) spectroscopy and principal component analysis (PCA). Pulp was treated with xylanase for 4–8 h with stirring at 30°C. Some samples were further extracted with NaOH for 1 h at 65°C. FTIR spectra were recorded directly from the dried pulp samples by using the diffuse reflectance technique. Reduction in kappa number of 69% was obtained after sequence xylanase (4 h)-alkaline extraction. During bleaching the viscosity decreased only 12%. FTIR-PCA showed that the first three principal components (PCs) explained more than 90% of the total variance of the pulp spectra. PC2×PC1 plot showed that the points related to pulps from sequence xylanase (4 h)-alkaline extraction are different from the other. This group isenlarged by plotting PC3×PC1 or PC3×PC2 containing all pulps submitted to alkaline extraction. PC2 and PC3 are the principal factor for differentiation of the pulps. These PCs suffer influence of the ester bands (1740 and 1244 cm⁻¹). On the other hand, the pulps bleached only with xylanase could not be differentiated from the nonbleached pulps.     

Sorption of spruce O-acetylated galactoglucomannans onto different pulp fibres

Sorption of spruce acetylated galactoglucomannans (GGM) onto different pulps, among which unbleached and peroxide-bleached mechanical pulps, and unbleached and bleached kraft (BK) pulps, was studied as a means of understanding the retention of acetylated GGMs in mechanical pulping and papermaking. The fibre surface coverage of lignin and carbohydrates was estimated by X-ray photoelectron spectroscopy (XPS) or electron spectroscopy for chemical analysis (ESCA). GGM sorption was clearly favoured on kraft pulps. Hardly any differences in sorption were, however, observed between unbleached and BK pulps, even if the surface coverage of lignin was lower on the bleached pulp. Neither thermomechanical pulp (TMP) nor chemithermomechanical pulp (CTMP) manufactured from spruce sorbed any acetylated GGMs. Peroxide bleaching of the pulp did not increase sorption. Only CTMP produced from aspen sorbed some GGMs. The anionic charge of neither chemical nor mechanical pulps influenced GGM sorption.     

Extracting biological information with computational analysis of Fourier-transform infrared (FTIR) biospectroscopy datasets: current practices to future perspectives

Applying Fourier-transform infrared (FTIR) spectroscopy (or related technologies such as Raman spectroscopy) to biological questions (defined as biospectroscopy) is relatively novel. Potential fields of application include cytological, histological and microbial studies. This potentially provides a rapid and non-destructive approach to clinical diagnosis. Its increase in application is primarily a consequence of developing instrumentation along with computational techniques. In the coming decades, biospectroscopy is likely to become a common tool in the screening or diagnostic laboratory, or even in the general practitioner's clinic. Despite many advances in the biological application of FTIR spectroscopy, there remain challenges in sample preparation, instrumentation and data handling. We focus on the latter, where we identify in the reviewed literature, the existence of four main study goals: Pattern Finding; Biomarker Identification; Imaging; and, Diagnosis. These can be grouped into two frameworks: Exploratory; and, Diagnostic. Existing techniques in Quality Control, Pre-processing, Feature Extraction, Clustering, and Classification are critically reviewed. An aspect that is often visited is that of method choice. Based on the state-of-art, we claim that in the near future research should be focused on the challenges of dataset standardization; building information systems; development and validation of data analysis tools; and, technology transfer. A diagnostic case study using a real-world dataset is presented as an illustration. Many of the methods presented in this review are Machine Learning and Statistical techniques that are extendable to other forms of computer-based biomedical analysis, including mass spectrometry and magnetic resonance.     

Noninvasive Surface Detection of Papillary Thyroid Carcinoma by Fourier Transform Infrared Spectroscopy

Previously Fourier transform infrared(FTIR) spectroscopy has been applied to detecting thyroid cancer during operations and to discriminating cervical metastatic ones from non-metastatic lymph nodes. This study explored the possibility of establishing a sensitive, accurate and noninvasive screen or diagnosis by preoperative FTIR spectroscopy. 111 patients undergone a thyroid operation and 50 healthy volunteers were enrolled in the study. The FTIR spectra were obtained by two mid-infrared optical fibers with an attenuated total reflectance(ATR) probe closely contacting the subjects' skin on the thyroid nodules. The FTIR spectra obtained from normal thyroid, nodular goiter(NG) and papillary thyroid carcinoma(PTC) patients were compared. A Fisher's discriminant analysis was created based on these data. There were 41 PTC patients and 70 NG patients according to their histopathological examinations. A total of 23(of 39) parameters were statistically different among the three groups(P<0.05). The F₁₃₀₀ and F₁₀₈₀ parameters were significantly different between the three groups. In total, 9 out of 39 FTIR parameters were selected as independent factors by the Wilks' lambda stepwise discriminant analysis. The discrimination accuracy of papillary thyroid carcinoma in the three groups was 88.8%. Surface detection of PTC by FTIR spectroscopy is feasible. FTIR spectroscopy can be used for rapid and noninvasive PTC screen and auxiliary diagnosis.     

丙三醇在Pt电极上吸附和氧化过程的原位FTIR反射光谱研究

运用电化学循环伏安(CV)和原位FTIR反射光谱方法, 研究了丙三醇在Pt电极上的氧化过程。结果指出, 丙三醇的氧化是一个复杂的表面过程。其间包括脱水、吸附、解离等步骤。根据CV和红外实验数据, 本文提出了Pt电极上丙三醇解离吸附的表面反应机理和不同电位下丙三醇氧化的分子过程。     

Compositional dynamics of a commercial wine fermentation using two-dimensional FTIR correlation analysis

We have demonstrated that compositional changes occurring during a commercial red wine fermentation can be effectively monitored using FTIR spectroscopy and modelled with the aid of two-dimensional correlation techniques. This study represents a novel application of two-dimensional spectroscopy and showed that the reaction rates for the conversion of fructose and glucose to alcohol were different, with the latter being more rapid. The use of a simple three-component model serves to aid interpretation of the data and the results obtained confirm the value of two-dimensional FTIR correlation spectroscopy as a chemometric tool which has considerable potential for process monitoring.     

乙二醇在铂电极上吸附和氧化过程的现场FTIR反射光谱研究(Ⅰ)──酸性介质

运用循环伏安法和现场FTIR反射光谱研究了酸性介质中乙二醇在铂电极上的吸附和氧化行为,指出乙二醇电催化氧化是通过解离吸附产物和反应中间体双途径机理进行的。经FTIR反射光谱检测,解离吸附产物为CO,反应中间体主要有CH₂OH─COOH和HOOC─COOH等。本文还在分子水平上解释了铂电极上乙二醇吸附和氧化循环伏安特征的内在原因。     

Earth pigments in painting: characterisation and differentiation by means of FTIR spectroscopy and SEM-EDS microanalysis

Analytical characterisation of natural earths (ochres, siennas, umbers and green earths) has been carried out using Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) coupled to an energy dispersive X-Ray spectrometer (EDS). The study of these pigments, which are found in works of art, is very important since it can shed light on their source or the pictorial technique used. FTIR spectroscopy is suitable for the identification and differentiation of ochres and siennas. According to the matrix of the sample, FTIR allows the classification of ochres into ochres containing kaolinite and ochres containing sulphate. One of the goals of this research has been to establish a relationship between the matrix and the source of the samples tested. SEM-EDS is probably a better technique than FTIR for characterising umbers and green earths since they do not exhibit significant differences when FTIR studies are performed.     

傅里叶变换红外光谱结合模式识别法快速鉴别食用油的真伪

采用傅里叶变换红外光谱(FTIR)结合簇类独立软模式识别技术(SIMCA)建立了真伪食用油的快速鉴别方法. 该方法依据FTIR 的指纹特性, 收集并分析了53 个合格食用油和13 个伪造食用油的FTIR 谱图; 通过对谱图取二阶导数和标准化处理, 主成分分析(PCA)提取特征变量; 采用SIMCA 方法分别随机选取43 个合格食用油和9 个伪食用油样品的FTIR 谱图组成训练集, 构建得到真伪食用油的SIMCA 分类模型. 该模型经过剩余10 个合格食用油和4 个伪食用油的验证, 正确识别率达到了100%. 说明FTIR 结合SIMCA 可能成为快速鉴别食用油真伪的一种新方法.     

FTIR spectroscopy coupled with multivariate classification methods to identify different powdered infant formulas adulterated with melamine and cyanuric acid

Fourier transform infrared spectroscopy (FTIR) is a nondestructive, simple, rapid, and cheap measurement technique for analysis of many multicomponent chemical systems, e.g., detection of adulterants in food samples. In this respect, this study proposes combining FTIR spectroscopy with multivariate classification methods for classification and discrimination of different samples of infant formulas adulterated by melamine or/and cyanuric acid. Different parametric and non-parametric multivariate classification methods including the linear discriminant analysis (LDA), partial least squares-discriminant analysis (PLS-DA), soft independent modeling of class analogy (SIMCA), K-nearest neighbors (KNN), and classification and regression tree (CART) approaches were used to classify the recorded FTIR data. Assessing the performance of the multivariate methods according to their sensitivity, specificity and percent of correct prediction results demonstrated that coupling FTIR spectroscopy with multivariate classification can be applied as a rapid and powerful technique to the simultaneous detection of melamine and cyanuric acid in powdered infant formulas. This combinatorial method is efficient for adulterant concentrations as low as 0.0001 w/w%.     

Use of ionic liquids in the study of fruit ripening by high-resolution 13C NMR spectroscopy: 'green' solvents meet green bananas

Banana pulps at any ripening stage can be completely dissolved in solvent systems based on the ionic liquid (IL) 1-n-butyl-3-methylimidazolium chloride ([C4mim]Cl), and variations in the carbohydrate composition of the fruit analyzed directly on the resulting solutions using high-resolution 13C NMR spectroscopy.     

Fourier transform Raman spectroscopic studies of a novel wood pulp bleaching system

The use of near-infrared (NIR) Fourier transform (FT) Raman spectroscopy for the study of lignocellulosic materials is discussed. An application utilizing NIR FT-Raman spectroscopy to study a novel chlorine-free process for the bleaching of wood pulps is presented in detail. The new process, still under development, entails the oxidation of residual lignin in wood pulps by vanadium-substituted polyoxometalates, and reoxidation of the reduced polyoxometalates by chlorine-free oxidants such as air, dioxygen, peroxides or ozone. Results from FT-Raman measurements of polyoxometalate-treated pulps are compared with those from chemical, spectroscopic and optical techniques commonly used in the pulp and paper industry.     

Cellulose crystallinity and ordering of hemicelluloses in pine and birch pulps as revealed by solid-state NMR spectroscopic methods

Solid-state ¹³C NMR spectroscopy was used to determine the degree of cellulose crystallinity (CrI) in kraft, flow-through kraft and polysulphide–anthraquinone (PS–AQ) pulps of pine and birch containing various amounts of hemicelluloses. The applicability of acid hydrolysis and the purely spectroscopic proton spin-relaxation based spectral edition (PSRE) method to remove the interfering hemicellulose signals prior to the determination of CrI were also compared. For softwood pulps, the spectroscopic removal of hemicelluloses by PSRE was found to be more efficient than the removal of hemicelluloses by acid hydrolysis. In addition to that, the PSRE method also provides information on the associations between cellulose and hemicelluloses. On the basis of the incomplete removal of xylan from the cellulose subspectra by PSRE, the deposition of xylan on cellulose fibrils and therefore an ordered ultrastructure of xylan in birch pulps was suggested. The ordered structure of xylan in birch pulps was also supported by the observed change of xylan conformation after regeneration. Similarly, glucomannan in pine pulps may have an ordered structure. According to the ¹³C CPMAS measurements conducted after acid hydrolysis, the degree of cellulose crystallinity was found to be slightly lower in birch pulps than in the pine pulps. Any significant differences in cellulose crystallinity were not found between the pulps obtained by the various pulping methods. Only in pine PS–AQ pulp, the degree of cellulose crystallinity may be slightly lower than in the kraft pulps containing less hemicelluloses.     

Characterisation of dissolving pulp using designed process variables, NIR and NMR spectroscopy, and multivariate data analysis

Two processability variables, filter clogging and alkali resistance, were measured in a series of laboratorycooked viscose pulps. The pulps were also characterised by ¹³CCP/MAS solid state nuclear magnetic resonance (NMR) and near infrared (NIR) spectroscopy. Partial least squares (PLS) regression was used to investigate the information provided by the spectroscopic methods with respect to the processability measurements. The study showed that the alkali resistance, R18, of the pulp and the filter clogging value, Kw, of the laboratoryprepared viscose can be modelled by NIR and multivariate data analysis (MVA). The alkali resistance, R18, of the pulp can also be calculated by NMR and partial least squares (PLS) regression. Analysis of the loading values in the PLS model showed that pulps with high alkali resistance have higher crystallinity than pulps with low alkali resistance. Analysis of variables of the cooking conditions showed that the chemical charge (Na₂O) and pH should be kept low to give high alkali resistance, whereas high Na₂O gives low filter clogging values.     

Ethanol determination in frozen fruit pulps: an application of quantitative nuclear magnetic resonance

This study reports the chemical composition of five types of industrial frozen fruit pulps (acerola, cashew, grape, passion fruit and pineapple fruit pulps) and compares them with homemade pulps at two different stages of ripening. The fruit pulps were characterized by analyzing their metabolic profiles and determining their ethanol content using quantitative Nuclear Magnetic Resonance (qNMR). In addition, principal component analysis (PCA) was applied to extract more information from the NMR data. We detected ethanol in all industrial and homemade pulps; and acetic acid in cashew, grape and passion fruit industrial and homemade pulps. The ethanol content in some industrial pulps is above the level recommended by regulatory agencies and is near the levels of some post‐ripened homemade pulps. This study demonstrates that qNMR can be used to rapidly detect ethanol content in frozen fruit pulps and food derivatives. Copyright © 2015 John Wiley & Sons, Ltd.     

Monitoring Fibre Surfaces with XPS in Papermaking Processes

 Recent instrumental advances have vastly improved the analysis power of X-ray photoelectron spectroscopy (XPS), which has been widely used in applied surface research for decades. In this presentation a set of XPS analysis methods well suited for problems and analytical needs encountered in papermaking technology is presented. The emphasis will be on analysis of pulps and non-coated papers. Examples given describe the use of XPS in quantification of surface lignin and extractives; an alternative approach for evaluating elemental surface distributions via the Tougaard background analysis is also presented. The experimental work and interpretations presented are based on more than two thousand XPS analyses performed at Helsinki University of Technology during 1996–2000. With strictly standardised experimental setup, state-of-the-art instrumentation and a proper combination of analysis methods XPS can yield valuable and consistent information on surface properties of natural fibers.     

ATR‐FTIR Kretschmann spectroscopy for interfacial studies of a hidden aluminum surface coated with a silane film and epoxy I. Characterization by IRRAS and ATR‐FTIR

Interfacial analysis is essential in many areas of interest, for instance within the ongoing research on environmentally friendly pretreatments of metal surfaces. While studies of the hidden interface between a metal and polymer top‐coat are of great importance, properties of a surface confined between two media are difficult to analyze in detail. Within the two parts of this study, ATR‐FTIR spectroscopy in the Kretschmann geometry is employed as the main analytical tool to study the interface between a thermo‐cured epoxy and aluminum pretreated with a silane film. The technique requires model systems based on thin metal films, but in contrast to most analytical techniques it permits the analysis of a hidden interface. Initial characterization of the silane film formed from a pH‐regulated γ‐APS and BTSE solution was conducted by both ATR‐FTIR Kretschmann and IRRAS spectroscopy. Absorption bands were obtained at 1250–900 cm^?1, assigned to Si? O functionalities, and at ～1570 and ～1410 cm^?1 assigned to acetate existing as a counter‐ion to γ‐APS. After application of the epoxy film, interfacial alterations were detected upon thermal curing including the densification of the epoxy film, the dehydration of aluminum and the formation of molecular epoxy reaction products. Few alterations could be assigned to the silane film. Calculated spectra derived from optical data can verify experimental results and aid data interpretation, and effects of metal oxidation of aluminum were confirmed by introducing gold as an additional substrate. The results showed that ATR‐FTIR Kretschmann spectroscopy is clearly a valuable tool for the study of hidden interfaces of stratified media. Copyright © 2011 John Wiley & Sons, Ltd.     

α-甲基苯乙烯-马来酸酐共聚物的合成及其引发的甲基丙烯酸甲酯的无皂乳液聚合

以α-甲基苯乙烯(AMS)、马来酸酐(MANH)为共聚单体,偶氮二异丁腈(AIBN)为引发剂,采用自稳定沉淀聚合法合成了α-甲基苯乙烯和马来酸酐的共聚物,再将其皂化后得到具有引发和乳化双重作用的共聚物.该共聚物可以作为大分子引发剂再引发甲基丙烯酸甲酯(MMA)进行无皂乳液聚合.采用扫描电镜、红外光谱仪、乌氏黏度计等仪器对AMS-MANH共聚物以及乳液聚合产物进行了表征.结果表明,乳液聚合产物是以PMMA为主长链,AMS和MANH低聚物为短链的嵌段共聚物.单体最高转化率可达到85%,特性黏数在80 mL/g左右.乳胶粒子粒径在150～200 nm之间.聚合速率随着引发剂浓度的增加而增大,聚合物的特性黏数随着转化率的提高基本呈线性增大.     

Electric field standing wave artefacts in FTIR micro-spectroscopy of biological materials

FTIR absorption micro-spectroscopy is a widely used, powerful technique for analysing biological materials. In principle it is a straightforward linear absorption spectroscopy, but it can be affected by artefacts that complicate the interpretation of the data. In this article, artefacts produced by the electric-field standing-wave (EFSW) in micro-reflection-absorption (transflection) spectroscopy are investigated. An EFSW is present at reflective metallic surfaces due to the interference of incident and reflected light. The period of this standing wave is dependent on the wavelength of the radiation and can produce non-linear changes in absorbance with increasing sample thickness (non-Beer-Lambert like behaviour). A protein micro-structure was produced as a simple experimental model for a biological cell and used to evaluate the differences between FTIR spectra collected in transmission and transflection. By varying the thickness of the protein samples, the relationship between the absorbance and sample thickness in transflection was determined, and shown to be consistent with optical interference due to the EFSW coupled with internal reflection from the sample top surface. FTIR spectral image data from MCF 7 breast adenocarcinoma cells was then analysed to determine the severity of the EFSW artefact in data from a real sample. The results from these measurements confirmed that the EFSW artefact has a profound effect on transflection spectra, and in this case the main spectral variations were related to the sample thickness rather than any biochemical differences.