Investigation of anthropic effects connected with metal ions concentration, organic matter and grain size in Bormida river sediments

An investigation on the sediment composition and grain size was carried out along the Bormida river (Piedmont, Northern Italy). The samples were taken both in the riverbed and on its banks. Multivariate statistical exploratory methods permitted to identify possible sources of primary pollution. In particular, principal component analysis (PCA) showed that there are probably at least three anthropogenic main causes of pollution, one connected with Cr, Ni and Sn, the second with cadmium and the last one with mercury. Some correlations were found between heavy metal ion concentrations and organic matter and/or the sediment grain size. Differences between the samples collected in the riverbed and on the banks were identified and the relationships between the principal components and the distance of the samples from the riverbed and from the hot spot represented by the ACNA industrial site were also analyzed.     

Influence of copper species on silver grain size in Ag–CuO–SiO2 ternary nanocomposites

The influence of Cu species on Ag grain size in Ag–CuO–SiO₂ ternary nanocomposites prepared by adsorbed-layer nanoreactor technique (ALRT)was investigated. Ag and CuO nanoparticles were synthesized on the silica surface one after the other, then the grain size of Ag was determined by X-ray diffraction. Ag grains became smaller with increase in amount of Cu, whether Cu species was fed before or after Ag species, implying that the grain growth of Ag was inhibited by the appearance of Cu(OH)₂ in both feeding sequences. Furthermore, after taken away the effect of alkaline concentration on Ag grain size, the inhibition effects of two feeding sequences become more similar.     

Evaluation of radiological hazards in the sediments of Ogun river, South-Western Nigeria

The concentrations of natural radionuclides in the sediments of Ogun river in South Western Nigeria have been measured and determined using gamma-ray spectrometry. The mean activity concentrations of ⁴⁰K, ²²⁶Ra, and ²³²Th at different locations along the course of the river were found to vary from 370.99±19.26 Bq/kg (at Olopade) to 608.02±24.66 Bq/kg (at Owere), 5.57±2.34 (at Ekerin) to 20.40±4.52 Bq/kg (at Sokori) and 5.04±2.24 Bq/kg (at mile 12-Maidan) to 23.10±4.81 Bq/kg (at Sokori) respectively. The overall calculated mean of the total indoor absorbed dose rates was 64.46±9.16 nGy/h with corresponding annual indoor effective dose of 0.32±0.05 mSv/y. Radium equivalent activity (Ra_eq), external hazard index (H_ex), internal hazard index (H_in) and representative gamma index (I_γr) were calculated in order to assess the radiation hazards associated with the use of these sediments in the construction of dwellings. The overall estimated values for the radium equivalent activity, external hazard index, internal hazard index and the representative gamma index were 67.96±10.74 Bq/kg, 0.18±0.03, 0.22±0.05 and 0.54±0.08, respectively. These values obtained for the river sediments were less than the recommended safe and criterion limits by UNSCEAR and also, they compared well with the values from other countries of normal radiation areas. It suffices to say therefore that sediments from Ogun river are safe and can be used for construction of buildings without undue radiological health concerns. Results of the study could serve as an important baseline radiometric data for future epidemiological studies and monitoring initiatives in the study area.     

Microwave assisted extraction and sonication of polychlorobiphenils from river sediments and risk assesment by toxic equivalency factors

Summary Microwave extraction and ultrasonication of dioxin-like polychlorobiphenyls (PCBs) from sediment samples were investigated. After separation of dioxin-like PCBs from a sample matrix on an acidic-alkaline silica gel column, dioxin-like PCBs were determined by GC-ECD, using dual capillary columns. Recoveries of dioxin-like PCBs in river sediment samples exceeded 80% by both extraction techniques. Toxic equivalency factors and their use for the PCB congeners investigated were applied. Presented at: Balaton Symposium on High-Performance Separation Methods, Siófok, Hungary, September 3–5, 1997     

Ultra-high-performance supercritical fluid chromatography-mass spectrometry for the analysis of organic contaminants in sediments

A nontarget screening method was developed based on D-optimal designs for ultra-high performance supercritical fluid chromatography with positive and negative electrospray ionization mode mass spectrometry. A mixture of organic contaminants such as pesticides, steroids, surfactants, phenolic and fatty acids, and polycyclic aromatic hydrocarbon derivatives, was used for the optimization. An aprotic mixture of dichloromethane and acetone [3:1] performed overall best as the injection solvent. The highest peak capacities (n) were accomplished at the shallowest gradient (1%B/min), ammonium formate (n = 378 in negative ionization mode), or ammonium acetate (n = 327 in positive ionization mode) in methanol as the modifier. Capillary voltage, make-up solvent flow rate, water, and additive concentration were the most significant factors for improving peak intensity: higher peak intensities were obtained at lower additive concentrations (5mM ammonium formate), and with 5% water in positive ionization mode. Conversely, water had detrimental effects in negative ionization mode. The optimized method was used to quantify organic contaminants in 17 freshwater sediment samples from Copenhagen, Denmark. Out of 50 monitored contaminants, 35 were detected in at least one sample. Further, the method has a potential for target and nontarget screening analysis of organic contaminants in solid matrices.     

Metals in water and surface sediments from Henan reaches of the Yellow River,China

The concentrations of Cd,Cr,Cu,Ni,Pb and Zn were determined in the water and surface sediments from the Henan reaches of the Yellow River.Twenty-three sampling sites along the Yellow River and its tributaries were selected.Generally,metal concentrations were found to decrease in sequences of Zn>Cu>Pb>Cr>Ni>Cd in water and Zn>Cr>Pb>Ni>Cu>Cd in sediments.High levels of metal concentration were determined at a few stations of the river and its tributaries,such as Yiluo River,Si River and Qin River.The pollutio...     

Thermal decomposition of native cellulose: Influence on crystallite size

The thermal degradation behavior of crystalline cellulose has been investigated using thermogravimetry, differential thermal analysis, and derivative thermogravimetry in a nitrogen atmosphere. Three cellulose samples, Halocynthia, cotton, and commercial microcrystalline cellulose Funacel, were used in this study to analyze the influence on crystallite size. They all belongs to cellulose I_β type and those crystallite sizes calculated from the X-ray diffractometry profiles by Scherrer equation were very different in the order Halocynthia > cotton > Funacel. The thermal decomposition of cellulose shifted to higher temperatures with increasing crystallite size. However, activation energies for the thermal degradation were the almost the same among the samples: 159-166 kJ mol⁻¹. These results indicated that the crystal structure does not affect the activation energy of the thermal degradation but the crystallite size affects the thermal degradation temperature.     

耐尔蓝-高碘酸钾催化光度法测定痕量钌

在磷酸介质和加热条件下,钌（Ⅲ）对高碘酸钾氧化耐尔蓝（ＮＢ）有强催化作用,详细研究了动力学条件,建立了动力学光度测定钌的新方法,１g（Ａ０／Ａ）与ＣＲu（Ⅲ）呈线性关系的范围为０．００８～１．２ｕｇ／Ｌ,检出限为０．００８ｒｇ／Ｌ,对０．００８和０．８ｕｇ／ＬＲｕ（Ⅲ）测定的ＲＳＤ分别为１４．３０％６和１．７３（n＝１１ ）。本催化反应对Ｒu（Ⅲ）、ＮＢ和ＫＩＯ４为一级反应,表观活化能为７３．４３ＫＪ     

Novel approaches to the analysis of steroid estrogens in river sediments

A wide range of estrogenic contaminants has been detected in the aquatic environment. Among these, natural and synthetic steroid estrogens, typically present in municipal sewage-treatment plant (STP) effluents, are the most potent. In this study a new GC–MS method has been developed for direct analysis of five major steroid estrogens (estrone, 17β-estradiol, 17α-ethinylestradiol, dienestrol, and diethylstilbestrol) in river sediments. Four GC–MS systems used for analysis of underivatized analytes in purified extracts were compared. Relatively low detection limits (1.5–5 ng g⁻¹ dried sediment) and good repeatability of GC splitless injection (RSD 1–2%) were achieved by use of a system combining low-pressure gas chromatography with a single-quadrupole mass analyzer (LP-GC–MS). Use of orthogonal gas chromatography (GC×GC) hyphenated with high-speed time-of-flight mass spectrometry (HSTOF-MS) enabled not only significantly better resolution of target analytes, and their unequivocal identification, but also further improvement (decrease) of their detection limits. In addition to these outcomes, use of this unique GC×GC–TOF-MS system enabled identification of several other non-target chemicals, including pharmaceutical steroids, present in purified sediment extracts.     

Morphological analysis of polymer systems with broad particle size distribution

This contribution is focused on precise determination of particle size distribution in polymer blends with complex morphology by means of our new program called MDISTR. Standard determination of the particle size distribution is usually achieved by measurement of particle sizes in (a single set of) electron micrographs. We show why this method fails for two frequent cases: (i) blends with very broad particle size distribution and (ii) blends that are composed of domains with different particle sizes. On real-life examples, we demonstrate that program MDISTR yields accurate particle size distributions in both the above-mentioned cases, while the standard image analysis gives average particle sizes differing by >100 % from the correct result. We describe MDISTR calculations which are based on a linear combination of standard particle size distributions from two (or more) sets of micrographs with different magnifications, different locations within the sample and precisely defined statistical weights.     

Influence of the pore size of reversed phase materials on peptide purification processes

The influence of the pore size of a chromatographic reversed phase material on the adsorption equilibria and diffusion of two industrially relevant peptides (i.e. a small synthetic peptide and insulin) has been studied using seven different reversed phase HPLC materials having pore sizes ranging from 90 Å to 300 Å. The stationary phase pore size distribution was obtained by inverse size exclusion measurement (iSEC). The effect of the pore size on the mass transfer properties of the materials was evaluated from Van Deemter experiments. It has been shown that the lumped mass transfer coefficient increases linearly with the average pore size. The Henry coefficient and the impurity selectivity were determined in diluted conditions. The saturation capacity of the main peptides was determined in overloaded conditions using the inverse method (i.e. peak fitting). It was shown that the adsorption equilibria of the peptides on the seven materials is well described by a surface-specific adsorption isotherm. Based on this a lumped kinetic model has been developed to model the elution profile of the two peptides in overloaded conditions and to simulate the purification of the peptide from its crude mixture. It has been found that the separation of insulin from its main impurity (i.e. desamido-insulin) was not affected by the pore size. On the other hand, in the case of the synthetic peptide, it was found that the adsorption of the most significant impurity decreases with the pore size. This decrease is probably due to an increase in silanol activity with decreasing pore size.     

Chemometrics characterisation of the quality of river water

Within the period from autumn 1990 to spring 1999 (from October to April in each period) 207 samples were collected and the measurement of 19 physical and chemical variables of the Mura river, Slovenia, were carried out. These variables are: river flow, water temperature, air temperature, dissolved oxygen, deficit of oxygen, oxygen saturation index, chemical oxygen demand (COD) in unfiltered and filtered samples, and biochemical oxygen demand after 5 days (BOD5) in unfiltered and filtered samples, pH, conductivity, ammonium, nitrite, nitrate, and phosphate concentrations, adsorbable organic halogens (AOX), dissolved organic carbon (DOC), and suspended solids. For handling the results of all measurements different chemometrics methods were employed: (i) the basic statistical methods for the determination of mean and median values, standard deviations, minimal and maximal values of measured variables, and their mutual correlation coefficients, (ii) the principal component analysis (PCA), and (iii) the clustering method based on Kohonen neural network. The influences of season, month, sampling site, and sampling time on the pollutant levels were examined. Before 1993, the pulp and paper industry was the main source of pollutants because of large amounts of chlorine emission as a consequence of industrial treatment, the leaching of cellulose. After the year 1993, the technology was changed and the quality of the river water has improved. The improvement could be detected 1 year after the change of technology. For one part of water samples the river quality classes based on biological parameters were also determined. The correlation between the biologically determined quality classes and chemical measurements was sought. Consequently, the biological classification for the water samples based on the chemical analyses was studied.     

悬浮液进样原子吸收光谱分析中样品的粒径效应

研究了悬浮液进样 FAAS和悬浮液进样 GFAAS中样品粒径效应。实验表明 ,悬浮液颗粒粒径 <30 μm能满足石墨炉原子化测定需要 ,而火焰原子化要求在粒径≤ 5 μm的前提下 ,再根据待测元素的性质选择合适的火焰类型 ,方能达到较满意的测定效果。     

An evaluation of kefir grain size with magnetic resonance imaging to observe the fermentation of milk

Kefirian milk is a fermented beverage consumed worldwide. Originally produced in animal skins, it is now prepared both industrially and at home by adding symbiotic cultures of bacteria and yeast known as kefir grains to fresh milk. There is significant literature on the biological aspects of this process but little focus on the fermentation effects on the bulk milk as a function of the grain morphology. Changes in the Magnetic Resonance (MR) signal as measured using a whole body clinical magnetic resonance imaging scanner are found to be proportional to traditional gas measurements with correlation coefficients in excess of 0.95. Magnetic Resonance Imaging is then also used to determine the effect of grain size on the rate of fermentation of milk. It is found that larger grains result in signal intensity changes on the order of 0.03 a.u per hour, but by breaking the grains into pieces around 3mm, the reaction rate can be more than doubled to 0.07 a.u. per hour. It is thought that this shows promise as a method to improve the speed of production of kefirian milk and by arresting the process partway through fermentation, gives control over the properties of the end product.     

耐尔兰A修饰碳纤维微柱电极的电化学性质研究

用循环伏安法将碳纤维柱电极表面官能团化，利用正负离子间的静电作用将耐尔兰Ａ修饰在碳纤维微柱电极（ＣＦＭＣＥ）表面，对该修饰电极的电化学性质进行研究，讨论了它的稳定性，测定了不同ＰＨ值下固定化耐尔兰Ａ电极反应的表现电子转移速率常数ｋ、电荷转移系数α以及参加电极反应的Ｈ＾＋数，实验表明：电极对血戏蛋白在ＣＦＭＣＥ上的还原有电催化作用。     

Influence of particle size distribution on thermokinetics of ilmenite with sulphuric acid reaction

The knowledge about kinetics of the reaction titanium raw materials with sulphuric acid is very important from the reason of influence of initial conditions of reaction on efficiency, quality and safety. One of the very important parameter, which influence on kinetics of this reaction is distribution of particles sizes of raw material. Presented results of investigation of reaction thermokinetics of ilmenite with different particles sizes, obtained in special construction of calorimeter, demonstrated very great influence of this parameter on rate of reaction with sulphuric acid. On the base of experimental investigation the kinetic model of this reaction was elaborated which takes into account density of particles sizes distribution described by the function of Rosin–Rammler. Presented model was tested on the base of experimental data of ilmenite with sulphuric acid reaction.     

A study of trace element contamination in river sediments in Serbia using microwave-assisted aqua regia digestion and multivariate statistical analysis

The aim of this study was the evaluation of the trace element contamination level in sediments of the most important rivers in Serbia and their tributaries. The determination of the aqua regia soluble contents of 12 micro- and macro-elements (Ca, Cd, Co, Cr, Cu, Fe, Mn, Pb, Ni, Zn, Be and V) in sediments was developed by the microwave digestion technique combined with inductively coupled plasma atomic emission spectrometry. Correlation analysis and principal component analysis distinguishes factors of lithogenic and anthropogenic origins. The Fe, Mn, Be and V contents are controlled by a regional lithogenic high background factor, while Cd, Cr, Pb, Ni, Zn and Cu are recognized as tracer of pollution. For Co, mixed sources from both lithogenic and anthropogenic inputs were evidenced.The investigated sediment of the major rivers and their tributaries in Serbia showed high concentrations of metals, especially of Cd, Pb, Cu and Zn, which may cause serious environmental impacts. Rivers which flow into the Danube from its entrance into Serbia significantly influence the chemical load of the water and sediments.The experimental study was conducted using two BCR standard reference materials. The calculated accuracy and precision confirmed the good performance of the adopted procedures.     

Influence of the particle size distribution on the CRTA curves for the solid-state reactions of interface shrinkage type

The kinetic curves at infinite temperature for the solid-state reactions of the interface shrinkage type were drawn theoretically by taking account the particle size distribution in the sample mixture. The CRTA curves for the reactions with the particle size distribution can be drawn by utilizing the universal kinetic curves at infinite temperature. The proper kinetic treatment for the CRTA curves with the particle size distribution is discussed in connection with the property of the kinetic equation with respect to the particle size distribution. The present kinetic consideration is taken as a simulation for the reactions with a certain distribution in among the reactant particles, produced preferably by the mass and heat transfer phenomena during the thermoanalytical measurements. The merit of the rate jump method by a single cyclic CRTA curve is also discussed on the basis of the present results.     

近红外光谱分辨率对定量分析的影响

利用近红外光谱建立了多组分混合物中对乙酰氨基苯酚和乙水杨胺的定量分析模型。定量模型可以快速准确地测定混合物中对乙酰氨基苯酚和乙水杨胺的含量。研究发现,光谱分辨率对定量分析模型有重要影响。以光谱分辨率4cm-1获得的光谱数据建立的对乙酰氨基苯酚定量模型,其校正集回归系数达到0·9992;其标准偏差为0.2120;同时模型的验证集回归系数为0.9996,而标准偏差达到0.1848。以分辨率1cm-1和8cm-1收集的光谱为基础获得的定量模型,其预测能力呈现不同程度下降趋势。研究结果表明,针对具体样品的特定组分,需要选择合适的光谱分辨率,进而获得最佳的定量分析结果。     

Influence of particle size on the crystallization process and the bioactive behavior of a bioactive glass system

Bioactive glasses have attracted considerable interest in recent years, due to their technological application, especially in biomaterials research. Differential scanning calorimetry (DSC) has been used in the study of the crystallization mechanism in the SiO₂–Na₂O–CaO–P₂O₅ glass system, as a function of particle size. The curve of the bulk glass presents a slightly asymmetric crystallization peak that could be deconvoluted into two separate peaks, their separation being followed in the form of powder glasses. Also, a shift of the crystallization peaks to lower temperatures was observed with the decrease of the particle size. FTIR studies – that are confirmed by XRD measurements – proved that the different peaks could be attributed to different crystallization mechanisms. Moreover, it is presented the bioactive behavior of the specific glass as a function of particle size. The study of bioactivity is performed through the process of its immersion in simulated human blood plasma (simulated body fluid, SBF) and the subsequent examination of the development of carbonate-containing hydroxyapatite layer on the surface of the particles. The bioactive response is improved with the increase of the particle size of powders up to 80 μm and remains almost unchanged for further increase, following the specific surface to volume ratio decrease.